Kittiwake

The Kittiwake geocache (GC4BAC0) plunges you — literally — into the clear waters of the Cayman Islands. Voted geocache of the week, this unusual container sits below sea level, at a depth of around 12 metres. To stand any chance of tracking it down, you need scuba gear or a solid command of free diving.

The treasure hides in the diving bell of the former USS Kittiwake, an American submarine rescue vessel commissioned in 1945 and decommissioned in 1994. The ship notably distinguished itself by recovering the black box of the space shuttle Challenger. Deliberately sunk in 2011 to form an artificial reef, it is home today to a highly varied marine life. The cache, held in a sturdy yellow diving box, was placed by a local instructor as a tribute to those who have lost their lives at sea.

One tip for your visit: remember to bring a pencil, because sea water has an unfortunate habit of destroying the ordinary pens left in the container. As for anecdotes, the cache owner once guided the famous astronaut Buzz Aldrin around the wreck. Aldrin amused himself by walking upside down against the hull, saying it was the closest thing to his steps on the Moon.

This adventure, hugely popular with the diving community, holds a great many favorite points and numerous visits, proof of its must-do status.

To explore further:

• The article on the official Geocaching blog devoted to this cache

• The official geocache page