[dainbramaged]

The shortest distance across the strait is nearly 8 miles, so swimmers better be in peak physical condition.
My brother and I swam across Hood Canal in Washington state for our Boy Scout mile swim patch back in 1966 - Dad accompanied us in a rowboat just in case.

[SunkenCiv]

I'd guess that there are rescue craft and crews along the route. Of course, maybe the guy selling the permits and promoting this just sits on a chaise lounge overlooking the ocean, laughing while puffin' a beeg ceegar and sipping booze out of a fake coconut...