diff --git a/components/src/preact/map/sequences-by-location-map.tsx b/components/src/preact/map/sequences-by-location-map.tsx
index 02db2644..99834584 100644
--- a/components/src/preact/map/sequences-by-location-map.tsx
+++ b/components/src/preact/map/sequences-by-location-map.tsx
@@ -1,10 +1,11 @@
 import type { Feature, FeatureCollection, GeometryObject } from 'geojson';
 import Leaflet, { type Layer, type LayerGroup } from 'leaflet';
 import type { FunctionComponent } from 'preact';
-import { useEffect, useRef } from 'preact/hooks';
+import { useEffect, useMemo, useRef } from 'preact/hooks';
 
 import { type GeoJsonFeatureProperties, type MapSource, useGeoJsonMap } from './useGeoJsonMap';
 import { type AggregateData } from '../../query/queryAggregateData';
+import { InfoHeadline1, InfoParagraph } from '../components/info';
 import { LoadingDisplay } from '../components/loading-display';
 import { formatProportion } from '../shared/table/formatProportion';
 
@@ -52,18 +53,27 @@ export const SequencesByLocationMapInner: FunctionComponent<SequencesByLocationM
 }) => {
     const ref = useRef<HTMLDivElement>(null);
 
-    useEffect(() => {
-        if (!ref.current || geojsonData === undefined || locationData === undefined) {
-            return;
-        }
-
+    const { locations, totalCount, countOfMatchedLocationData, unmatchedLocations } = useMemo(() => {
         const countAndProportionByCountry = buildLookupByLocationField(locationData, lapisLocationField);
-        const locations = matchLocationDataAndGeoJsonFeatures(
+        const { locations, unmatchedLocations } = matchLocationDataAndGeoJsonFeatures(
             geojsonData,
             countAndProportionByCountry,
             lapisLocationField,
         );
 
+        const totalCount = locationData.map((value) => value.count).reduce((sum, b) => sum + b, 0);
+        const countOfMatchedLocationData = locations
+            .map((location) => location.properties.data?.count ?? 0)
+            .reduce((sum, b) => sum + b, 0);
+
+        return { locations, totalCount, countOfMatchedLocationData, unmatchedLocations };
+    }, [geojsonData, locationData, lapisLocationField]);
+
+    useEffect(() => {
+        if (!ref.current) {
+            return;
+        }
+
         const leafletMap = Leaflet.map(ref.current, {
             scrollWheelZoom: enableMapNavigation,
             zoomControl: enableMapNavigation,
@@ -88,9 +98,82 @@ export const SequencesByLocationMapInner: FunctionComponent<SequencesByLocationM
         return () => {
             leafletMap.remove();
         };
-    }, [ref, locationData, geojsonData, enableMapNavigation, lapisLocationField, zoom, offsetX, offsetY]);
+    }, [ref, locations, enableMapNavigation, lapisLocationField, zoom, offsetX, offsetY]);
 
-    return <div ref={ref} className='h-full' />;
+    const nullCount = locationData.find((row) => row[lapisLocationField] === null)?.count ?? 0;
+
+    return (
+        <div className='h-full'>
+            <div ref={ref} className='h-full' />
+            <div className='relative'>
+                <DataMatchInformation
+                    totalCount={totalCount}
+                    countOfMatchedLocationData={countOfMatchedLocationData}
+                    unmatchedLocations={unmatchedLocations}
+                    nullCount={nullCount}
+                />
+            </div>
+        </div>
+    );
+};
+
+type DataMatchInformationProps = {
+    totalCount: number;
+    countOfMatchedLocationData: number;
+    unmatchedLocations: string[];
+    nullCount: number;
+};
+
+const DataMatchInformation: FunctionComponent<DataMatchInformationProps> = ({
+    totalCount,
+    countOfMatchedLocationData,
+    unmatchedLocations,
+    nullCount,
+}) => {
+    const dialogRef = useRef<HTMLDialogElement>(null);
+
+    const proportion = formatProportion(countOfMatchedLocationData / totalCount);
+
+    return (
+        <>
+            <button
+                onClick={() => dialogRef.current?.showModal()}
+                className='text-sm absolute bottom-0 px-1 z-[1001] bg-white rounded border cursor-pointer tooltip'
+                data-tip='Click for detailed information'
+            >
+                This map shows {proportion} of the data.
+            </button>
+            <dialog ref={dialogRef} className={'modal modal-middle'}>
+                <div className='modal-box sm:max-w-3xl'>
+                    <InfoHeadline1>Sequences By Location - Map View</InfoHeadline1>
+                    <InfoParagraph>
+                        The current filter has matched {totalCount.toLocaleString('en-us')} sequences. We were able to
+                        match {countOfMatchedLocationData.toLocaleString('en-us')} sequences ({proportion}) on locations
+                        on the map.
+                    </InfoParagraph>
+                    {unmatchedLocations.length > 0 && (
+                        <InfoParagraph>
+                            The following locations from the data could not be matched on the map:{' '}
+                            {unmatchedLocations.map((it) => `"${it}"`).join(', ')}
+                        </InfoParagraph>
+                    )}
+                    {nullCount > 0 && (
+                        <InfoParagraph>
+                            {nullCount.toLocaleString('en-us')} matching sequences have no location information.
+                        </InfoParagraph>
+                    )}
+                    <div className='modal-action'>
+                        <form method='dialog'>
+                            <button className={'float-right underline text-sm hover:text-blue-700 mr-2'}>Close</button>
+                        </form>
+                    </div>
+                </div>
+                <form method='dialog' className='modal-backdrop'>
+                    <button>Helper to close when clicked outside</button>
+                </form>
+            </dialog>
+        </>
+    );
 };
 
 function buildLookupByLocationField(locationData: AggregateData, lapisLocationField: string) {
@@ -139,7 +222,7 @@ function matchLocationDataAndGeoJsonFeatures(
         console.warn(unmatchedLocationsWarning); // eslint-disable-line no-console -- We should give some feedback about unmatched location data.
     }
 
-    return locations;
+    return { locations, unmatchedLocations };
 }
 
 function getColor(value: number | undefined): string {
diff --git a/components/src/web-components/visualization/gs-sequences-by-location.stories.ts b/components/src/web-components/visualization/gs-sequences-by-location.stories.ts
index 31a28116..a9b90020 100644
--- a/components/src/web-components/visualization/gs-sequences-by-location.stories.ts
+++ b/components/src/web-components/visualization/gs-sequences-by-location.stories.ts
@@ -84,7 +84,7 @@ const Template: StoryObj<SequencesByLocationProps> = {
     args: {
         enableMapNavigation: false,
         width: '1100px',
-        height: '800px',
+        height: '700px',
         views: ['map', 'table'],
         pageSize: 10,
     },
@@ -150,7 +150,7 @@ export const Germany: StoryObj<SequencesByLocationProps> = {
             topologyObjectsKey: 'deu',
         },
         views: ['map', 'table'],
-        zoom: 6.3,
+        zoom: 6,
         offsetX: 10,
         offsetY: 51.4,
     },
diff --git a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-chromium-linux.png b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-chromium-linux.png
index 4548a76b..2e0b0514 100644
Binary files a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-chromium-linux.png and b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-chromium-linux.png differ
diff --git a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-firefox-linux.png b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-firefox-linux.png
index 22c727a6..7ddda238 100644
Binary files a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-firefox-linux.png and b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--germany-should-match-screenshot-1-firefox-linux.png differ
diff --git a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-chromium-linux.png b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-chromium-linux.png
index aa47ab0f..a4ca4688 100644
Binary files a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-chromium-linux.png and b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-chromium-linux.png differ
diff --git a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-firefox-linux.png b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-firefox-linux.png
index 5b0e8b81..9f665644 100644
Binary files a/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-firefox-linux.png and b/components/tests/snapshots.spec.ts-snapshots/Sequences-by-location-Story-visualization-sequences-by-location--world-map-should-match-screenshot-1-firefox-linux.png differ