Do not go unless a very calm wind/wave day (I'm saying less than 2-3 ft waves max). We made the mistake last New Years of going in one of the smaller craft (34 ft) and to be honest it was so rough (3+ meter waves) it could have been our last day. It was that dangerous and zero fun and no enjoyment. All pax got sick.
Basically I was told the water goes from very deep thousands of feet to hundreds of feet in that area creating the rough potential. Add 9 ft waves and 30/40 mph winds. Lookout.
As for booking in advance, the rental cars may be hard to get in high season. If you really want to go, I'd fly over out of grand case. 15 minutes. That I would book both flights/ car ahead.
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