Actually the crossing from Miami to Bimini from Government Cut in Miami to Alice Town on Bimini is 52 miles. Small boats make that crossing regularly. From Bimini you can make slightly longer jumps to the other islands. Crossing from Miami to Bimini you cross the Gulf stream and have to compensate for the northward current of the stream. On a jet ski fuel might be an issue but guys go out to the sunken carrier Oriskany fishing and it's 25 miles off Pensacola on jet skies.
I once came across two guys in a 14 foot flat boat fishing a rig 30 miles out in the Gulf.