Geocaching and the Mundane Monday challenge are a good match. I was looking for a cache to keep my streak going (I’ve now gone 123 consecutive days with a find), and I found a great caching series based on the planets. The cache for the sun is located in downtown San Jose, Mercury is a mile away, and caches for the other planets up to Neptune are placed at proportional distances away from the sun. Each planet’s cache also has clues in its logbook, and when you find the cache, you write down its clues so that when you add the clues up, you will get the coordinates for a Halley’s Comet cache. I have to find that one!