Retra is a European company best known for their optical snoots and other innovative accessories for the underwater photographer, such as the uTrigger underwater remote release.
Underwater Camera Floods: Avoiding the High Water Mark
No subject scares underwater photographers more than having an expensive housed camera turn into an aquarium. Even a bit of water can turn electronics into a corroded mess.
Here are a few general tips on maintenance that should help you avoid finding Nemo in your housing