diff --git a/data/activities.py b/data/activities.py
index c44e16e..0e5c7c2 100644
--- a/data/activities.py
+++ b/data/activities.py
@@ -12,6 +12,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         # any spots with "contest" in the comment will get allocated to this activity.
         comment_names=["CONTEST"],
         icon="fa-trophy",
+        alerts_possible=True,
     ),
     ActivityName.DXPEDITION: Activity(
         name=ActivityName.DXPEDITION,
@@ -23,6 +24,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         # this activity to a spot other ways.
         comment_names=[],
         icon="fa-book-atlas",
+        alerts_possible=True,
     ),
     ActivityName.SATELLITE: Activity(
         name=ActivityName.SATELLITE,
@@ -32,6 +34,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         refs_globally_unique=False,
         comment_names=[],
         icon="fa-satellite",
+        alerts_possible=True,
     ),
     ActivityName.EME: Activity(
         name=ActivityName.EME,
@@ -70,6 +73,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         refs_globally_unique=False,
         comment_names=["QRP"],
         icon="fa-volume-low",
+        alerts_possible=True,
     ),
     ActivityName.POTA: Activity(
         name=ActivityName.POTA,
@@ -81,6 +85,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"[A-Z]{2}\-\d{4,5}|K\-TEST",
         comment_names=["POTA"],
         icon="fa-tree",
+        alerts_possible=True,
     ),
     ActivityName.SOTA: Activity(
         name=ActivityName.SOTA,
@@ -92,6 +97,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"[A-Z0-9]{1,3}\/[A-Z]{2}\-\d{3}",
         comment_names=["SOTA"],
         icon="fa-mountain-sun",
+        alerts_possible=True,
     ),
     ActivityName.WWFF: Activity(
         name=ActivityName.WWFF,
@@ -103,6 +109,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"[A-Z0-9]{1,3}FF\-\d{4}",
         comment_names=["WWFF"],
         icon="fa-seedling",
+        alerts_possible=True,
     ),
     ActivityName.GMA: Activity(
         name=ActivityName.GMA,
@@ -136,6 +143,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"[A-Z0-9]{1,3}\/[A-Z]{3}\-\d{3}",
         comment_names=["HEMA"],
         icon="fa-mound",
+        alerts_possible=True,
     ),
     ActivityName.IOTA: Activity(
         name=ActivityName.IOTA,
@@ -202,6 +210,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"[A-Z]{2}\-[A-Z]{3}\d",
         comment_names=["SIOTA"],
         icon="fa-wheat-awn",
+        alerts_possible=True,
     ),
     ActivityName.WCA: Activity(
         name=ActivityName.WCA,
@@ -225,6 +234,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         comment_names=["ZLOTA"],
         icon="fa-kiwi-bird",
         region_flag="🇳🇿",
+        alerts_possible=True,
     ),
     ActivityName.WOTA: Activity(
         name=ActivityName.WOTA,
@@ -237,6 +247,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         comment_names=["WOTA"],
         icon="fa-w",
         region_flag="🇬🇧",
+        alerts_possible=True,
     ),
     ActivityName.BOTA: Activity(
         name=ActivityName.BOTA,
@@ -247,6 +258,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_type=ActivityRefType.BEACH,
         comment_names=[],
         icon="fa-umbrella-beach",
+        alerts_possible=True,
     ),
     ActivityName.KRMNPA: Activity(
         name=ActivityName.KRMNPA,
@@ -259,6 +271,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         comment_names=["KRMNPA"],
         icon="fa-earth-oceania",
         region_flag="🇦🇺",
+        alerts_possible=True,
     ),
     ActivityName.SANPCPA: Activity(
         name=ActivityName.SANPCPA,
@@ -271,6 +284,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         comment_names=["SANPCPA"],
         icon="fa-earth-oceania",
         region_flag="🇦🇺",
+        alerts_possible=True,
     ),
     ActivityName.LLOTA: Activity(
         name=ActivityName.LLOTA,
@@ -282,6 +296,7 @@ ACTIVITIES: dict[ActivityName, Activity] = {
         ref_regex=r"LL[A-Z]{2}\-\d{4}",
         comment_names=["LLOTA"],
         icon="fa-water",
+        alerts_possible=True,
     ),
     ActivityName.TOWERS: Activity(
         name=ActivityName.TOWERS,
diff --git a/data/activity.py b/data/activity.py
index a36efce..c0e2fb0 100644
--- a/data/activity.py
+++ b/data/activity.py
@@ -43,3 +43,7 @@ class Activity:
     # Emoji flag for the country or region where this activity is relevant, if any. If None, this implies the
     # activity is in worldwide usage.
     region_flag: str | None = None
+    # Can alerts ever have this activity? A lot of activities can be figured out from spot comments but can never
+    # occur in alerts, so to avoid showing all activities on the "upcoming" page, we allow it to filter based on
+    # this.
+    alerts_possible: bool = False
diff --git a/static/apidocs/openapi.yml b/static/apidocs/openapi.yml
index ffea99f..7faecb5 100644
--- a/static/apidocs/openapi.yml
+++ b/static/apidocs/openapi.yml
@@ -20,6 +20,7 @@ info:
     * Renamed AMSAT SIG to "Satellite" as AMSAT is a specific organisation not just a general term for satellite QSOs
     * Removed `alert_type` from alert data. Contest, DXpedition and Satellite alerts now give those values in `sig` instead, alongside the existing outdoor activity programmes. Teeeeechnically a breaking change but AlertType is so new I doubt anyone is using it yet, so slipped this one in anyway. Sorry :)
     * Added QRP, RaDAR Rally, /AM and /MM activities
+    * Added `has_refs` and `alerts_possible` to Activity data
 
     ### 2.1
     
@@ -1604,6 +1605,15 @@ components:
             specific event (e.g. MOTA). Generally for Spothole's own internal use, clients probably won't need this.
             Used to group them in the web UI. Still named "sig_type" in the API for backwards compatibility.
           $ref: "#/components/schemas/ActivityType"
+        has_refs:
+          type: boolean
+          description: >
+            Whether this activity has a fixed set of references (e.g. parks, summits) with an ID that gets
+            "activated", as opposed to activities like Contest or DXpedition which don't.
+        ref_type:
+          description: >
+            The type of reference that gets activated for this activity, e.g. Park or Summit.
+          $ref: "#/components/schemas/ActivityRefType"
         comment_names:
           type: array
           description: >
@@ -1639,6 +1649,11 @@ components:
             Flag emoji, if this activity is specific to a country or region. If null, this activity is treated as
             worldwide.
           example: "🇺🇳"
+        alerts_possible:
+          type: boolean
+          description: >
+            Whether alerts can ever have this activity. While Spothole can assign any activity from spot comments, there
+            are only a limited set that can ever crop up in alerts, because we don't parse general comments for alerts.
 
     SolarConditions:
       type: object
diff --git a/static/js/alerts.js b/static/js/alerts.js
index 09a58c7..a8f0c4a 100644
--- a/static/js/alerts.js
+++ b/static/js/alerts.js
@@ -332,7 +332,8 @@ function loadOptions() {
         // Populate the filters panel
         generateMultiToggleFilterCard("#dx_continent_options", "dx_continent", options["continents"]);
         generateMultiToggleFilterCard("#source-options", "source", options["alert_providers"]);
-        generateActivitiesMultiToggleFilterCard(options["sigs"]);
+        // Alerts can only ever be tagged with activities that have an alert source, so only offer those as filters here
+        generateActivitiesMultiToggleFilterCard(options["sigs"].filter(o => o["alerts_possible"]), false);
 
         // Load URL params. These may select things from the various filter & display options, so the function needs
         // to be called after these are set up, but if the URL params ask for "embedded mode", this will suppress
diff --git a/static/js/common.js b/static/js/common.js
index b5d50c6..d81d30c 100644
--- a/static/js/common.js
+++ b/static/js/common.js
@@ -136,8 +136,12 @@ function generateMultiToggleFilterCard(elementID, filterQuery, options) {
 }
 
 // Generate a collapsable section for the activities filter card, and append it to the given list. The section is
-// expanded by default if isExpanded is true.
-function appendActivityFilterSection($list, sectionId, heading, isExapanded, buildBody) {
+// expanded by default if isExpanded is true. If hasContent is false (i.e. there are no activities to show in this
+// section), the section is omitted entirely rather than showing an empty collapsible heading.
+function appendActivityFilterSection($list, sectionId, heading, isExapanded, hasContent, buildBody) {
+    if (!hasContent) {
+        return;
+    }
     const collapseId = `activity-options-${sectionId}-collapse`;
     const $li = $('<li class="mb-1">');
     $li.append(`<button class="btn-toggle${isExapanded ? '' : ' collapsed'}" data-bs-toggle="collapse" data-bs-target="#${collapseId}" aria-expanded="${isExapanded ? 'true' : 'false'}" aria-controls="${collapseId}">${heading}</button>`);
@@ -147,45 +151,42 @@ function appendActivityFilterSection($list, sectionId, heading, isExapanded, bui
     $list.append($li);
 }
 
-// Generate activities filter card. This one is also a special case.
-function generateActivitiesMultiToggleFilterCard(activity_options) {
+// Build the grid of activity checkboxes for a given (already filtered) list of activities.
+function buildActivityFilterGrid(activity_options) {
+    const $grid = $('<div class="row row-cols-2 g-1 mb-1">');
+    activity_options.forEach(o => {
+        const domSafeName = o["name"].replace(/^[^A-Za-z0-9]+|[^\w]+/gi, "");
+        $grid.append(`<div class="col"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-${domSafeName}" value="${o['name']}" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-${domSafeName}" for="filter-button-sig-${domSafeName}" title="${o['description']}"><i class="fa-solid ${o['icon']}"></i> ${o['name']} ${(o["region_flag"] != null) ? o['region_flag'] : ''}</label></div></div>`);
+    });
+    return $grid;
+}
+
+// Generate activities filter card. This one is also a special case. includeGeneralDX controls whether the "General
+// DX" (NO_SIG) option is offered - this doesn't apply on the alerts page, where every alert has an activity.
+function generateActivitiesMultiToggleFilterCard(activity_options, includeGeneralDX = true) {
     const $list = $('<ul class="list-unstyled filter-section-list ps-0">');
 
-    appendActivityFilterSection($list, 'traditional', 'Traditional', true, $body => {
-        const $grid = $('<div class="row row-cols-2 g-1 mb-1">');
-        activity_options.filter(o => o["sig_type"] === "TRADITIONAL").forEach(o => {
-            const domSafeName = o["name"].replace(/^[^A-Za-z0-9]+|[^\w]+/gi, "");
-            $grid.append(`<div class="col"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-${domSafeName}" value="${o['name']}" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-${domSafeName}" for="filter-button-sig-${domSafeName}" title="${o['description']}"><i class="fa-solid ${o['icon']}"></i> ${o['name']} ${(o["region_flag"] != null) ? o['region_flag'] : ''}</label></div></div>`);
-        });
-        $body.append(`<div class="w-100 mb-1"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-NO_SIG" value="NO_SIG" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-NO_SIG" for="filter-button-sig-NO_SIG"><i class="fa-solid fa-tower-cell"></i> General DX</label></div></div>`);
-        $body.append($grid);
+    const traditional = activity_options.filter(o => o["sig_type"] === "TRADITIONAL");
+    appendActivityFilterSection($list, 'traditional', 'Traditional', true, includeGeneralDX || traditional.length > 0, $body => {
+        if (includeGeneralDX) {
+            $body.append(`<div class="w-100 mb-1"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-NO_SIG" value="NO_SIG" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-NO_SIG" for="filter-button-sig-NO_SIG"><i class="fa-solid fa-tower-cell"></i> General DX</label></div></div>`);
+        }
+        $body.append(buildActivityFilterGrid(traditional));
     });
 
-    appendActivityFilterSection($list, 'adventure', 'Adventure', true, $body => {
-        const $grid = $('<div class="row row-cols-2 g-1 mb-1">');
-        activity_options.filter(o => o["sig_type"] === "ADVENTURE").forEach(o => {
-            const domSafeName = o["name"].replace(/^[^A-Za-z0-9]+|[^\w]+/gi, "");
-            $grid.append(`<div class="col"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-${domSafeName}" value="${o['name']}" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-${domSafeName}" for="filter-button-sig-${domSafeName}" title="${o['description']}"><i class="fa-solid ${o['icon']}"></i> ${o['name']} ${(o["region_flag"] != null) ? o['region_flag'] : ''}</label></div></div>`);
-        });
-        $body.append($grid);
+    const adventure = activity_options.filter(o => o["sig_type"] === "ADVENTURE");
+    appendActivityFilterSection($list, 'adventure', 'Adventure', true, adventure.length > 0, $body => {
+        $body.append(buildActivityFilterGrid(adventure));
     });
 
-    appendActivityFilterSection($list, 'regional', 'Regional', false, $body => {
-        const $grid = $('<div class="row row-cols-2 g-1 mb-1">');
-        activity_options.filter(o => o["sig_type"] === "REGIONAL").forEach(o => {
-            const domSafeName = o["name"].replace(/^[^A-Za-z0-9]+|[^\w]+/gi, "");
-            $grid.append(`<div class="col"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-${domSafeName}" value="${o['name']}" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-${domSafeName}" for="filter-button-sig-${domSafeName}" title="${o['description']}"><i class="fa-solid ${o['icon']}"></i> ${o['name']} ${(o["region_flag"] != null) ? o['region_flag'] : ''}</label></div></div>`);
-        });
-        $body.append($grid);
+    const regional = activity_options.filter(o => o["sig_type"] === "REGIONAL");
+    appendActivityFilterSection($list, 'regional', 'Regional', false, regional.length > 0, $body => {
+        $body.append(buildActivityFilterGrid(regional));
     });
 
-    appendActivityFilterSection($list, 'event', 'Event', false, $body => {
-        const $grid = $('<div class="row row-cols-2 g-1 mb-1">');
-        activity_options.filter(o => o["sig_type"] === "EVENT").forEach(o => {
-            const domSafeName = o["name"].replace(/^[^A-Za-z0-9]+|[^\w]+/gi, "");
-            $grid.append(`<div class="col"><div class="form-check"><input type="checkbox" class="form-check-input filter-button-sig storeable-checkbox" id="filter-button-sig-${domSafeName}" value="${o['name']}" autocomplete="off" onClick="filtersUpdated()" checked><label class="form-check-label" id="filter-button-label-sig-${domSafeName}" for="filter-button-sig-${domSafeName}" title="${o['description']}"><i class="fa-solid ${o['icon']}"></i> ${o['name']} ${(o["region_flag"] != null) ? o['region_flag'] : ''}</label></div></div>`);
-        });
-        $body.append($grid);
+    const event = activity_options.filter(o => o["sig_type"] === "EVENT");
+    appendActivityFilterSection($list, 'event', 'Event', false, event.length > 0, $body => {
+        $body.append(buildActivityFilterGrid(event));
     });
 
     $("#activity-options").append($list);