electrical tape wont do shit against such pressure....
you're better off making sure that the seal inside is clean, 1 hair between the seal and casing = flooded housing ....
an as mentioned, you'll need to color correct the footage...
i'm an aspiring diving photographer and from around 10m i use a bright red filter, if you would use it on the surface, your pics are all red, but at depth they turn out fine :)
it's very weird ....