Animal Care/Land hermit crab terrarium

Besides glass tanks the only good, commercially-available hermit crab home is the Exo Terra Terrarium. A full setup can be seen at the site of this UK owner. The front doors give easy access to the crabs and make the units easy to clean. However, there are some reservations: expense,  humidity control, substrate depth, and the background piece.
 * The units come with a mesh lid, so you need to cover part of the mesh or provide a glass lid to retain humidity. Also, the glass doors do not seal to each other (but do lock securely).
 * The crabs may destroy the background piece.

The smallest unit appropriate for hermit crabs (12"W x 12"D x 18"H) is built for 4" of substrate. (Larger units allow more.) The limitation comes from the height of the door and the design of the ventilation system (keeps front doors free of moisture), but the units are strong enough to hold more substrate (according to the manufacturer). For instance, the unit mentioned above is strong enough for 6" of sand. The sand could simply be banked with only 4" at the front or the unit can be modified for 6" of sand by adding additional pieces of glass.

Aquarium sealant can be used to install a large piece of glass (approximately 12"W x 6"H) vertically across the unit 3" from the front. Then two glass pools can be put into the 3" front strip (with the middle of the strip available for other use).
 * Two smaller glass pieces (4"H x 3"W) can be installed vertically 4" from the sides. -or-
 * Two, small, removable glass pools (approximately 3"W x 4"L x 4"H) can be constructed to slip tightly into the strip.

There are a multitude of ways to help the crabs climb into the pools. Wood and rocks in the pools, plus a sponge in the fresh water, would give the crabs ways to climb out. To put bubblers in the pools, put small tubing holes in the large glass piece before installing it.

Of course, the sand could simply be banked around the removable glass pools, but that would make them more difficult to empty and, more importantly, one would loose an opportunity to encourage the crabs to climb and exercise.

If permanent installation of the large glass piece is not desired, it could be braced between the removable glass pools and the sand behind it. Additional pieces of glass (3"W x 4"H and/or 3"W x 6"H) would be needed to stabilize the setup, so that the glass pools could be removed and emptied without the large glass piece moving.