Divers often enter the sea armed with various bits of kit – and fancy dive computers with big screens can be expensive. Diveroid mini ($89) wants to simplify things. The device looks like a metal limpet clamped to a smartphone’s waterproof housing, and is waterproof to 60m. It works in conjunction with an Android/iOS app, so you can monitor water temperature, depth and decompression stops, and use a compass to avoid getting lost when you spot a particularly exciting fish in the distance. And when you do end up gawping at something really special, Diveroid mini calibrates your videos and photos, bringing back colour to underwater shoots. Back on the surface, its final trick is automatically creating a logbook, so you don’t have to bother, and can concentrate on more important tasks – like uploading your dive pics to make your friends green with envy.