The reefs are close to shore in many places and you can get a good maps that point out reef locations at the Maui Dive Shop .
Snorkeling is better in the morning before the trade winds pick up.
Water temp was cool, but I only wore a swim suit, and didn't need the shorty I brought. A lot of nice restaurants to choose from. The West side of the island is where snorkeling and diving is good. The end of April is when the whale watching ends. Sandals, shorts and tees were what we wore, except to go to nicer dinning establishments.