Aquatech housing for 1DX or 5DS?

Hey guys, I'm thinking about adding a water housing for my 1DX or my 5DS to my kit from Aquatech but am pretty lost with this, do any of you guys own a Aquatech water housing? what should I know? and what's the best lens to use with one?

I'm not giving a lot of info but I honestly think I'll just be using it for shots in northern norway and maybe iceland in the water for some cold water surf shots so been thinking about using a 24mm 1.4 ii with it for that.