In October Veho launched a waterproof case for the Muvi Micro.  It does cost quite a lot at £39.99, but I am sure this price will be come discounted in the future.  The waterproof case will allow you to take the camera up to 10 meters under water, so will be perfect for scuba diving trips, water sports, or for using the Muvi Micro on a typical British summer day ;).

Below is a fantastic video review of the waterproof case and using it with the helmet mount.