diff --git a/web/src/sw.ts b/web/src/sw.ts
index 4dc6da9..7dcb7e6 100644
--- a/web/src/sw.ts
+++ b/web/src/sw.ts
@@ -1,6 +1,6 @@
 import { createHandlerBoundToURL, precacheAndRoute, cleanupOutdatedCaches } from 'workbox-precaching'
 import { clientsClaim } from 'workbox-core'
-import { StaleWhileRevalidate } from 'workbox-strategies'
+import { StaleWhileRevalidate, CacheFirst } from 'workbox-strategies'
 import { registerRoute } from 'workbox-routing'
 
 declare let self: ServiceWorkerGlobalScope
@@ -20,6 +20,8 @@ register('capabilities/buildmap', new StaleWhileRevalidate())
 
 register('maps', new StaleWhileRevalidate({ cacheName: 'maps-20240527' }))
 
+register('data', new CacheFirst({ cacheName: 'basemaps-20240529' }))
+
 try {
     // Only catch requests to the root URL (a regex doesn't do this).
     registerRoute(