Molokini is far enough off shore to necessitate taking a boat. Don't try and swim or snorkel to the crater! It's much too far and strong channel currents can sweep you away. Once in the crater, the water is calm and safe. Only drive to Molokini if you're James Bond.
There are many vessels that can take you to the crater on pretty much any day. You'll want to go on a calmer day and the earlier the better. We also suggest taking a catamaran as opposed to a single-hull vessel. This way, you get less of the rocking and more stability. Pride of Maui has some excellent trips at great prices. We like them for many reasons, some being: