Good question! The very best time to go out to see and snorkel Molokini Crater is in the morning. This is the time when the oceans are calmest and the winds are least. The afternoon time can be a real wind fest at times, so much so in fact that the tours will have to be cancelled and re-routed to a different location. The alternate site is usually at an area just off the cliffs near the harbor below Hwy 30 which wraps around the island from Maalaea to Lahaina. This is actually a fairly nice snorkel location but if you are looking forward to Molokini you may be disappointed. Also, most of the morning Molokini tours include a nice lunch and go to another location off the coast of south Maui often referred to as Turtle Town. The afternoon snorkels usually just serve snacks.
What is the difference between the AM and PM Molokini snorkels?