Just off the presses: The NOAA is considering removing Humpback whales from the endangered list. The whale population has been increasing very rapidly over the past few years. In early March, the waters between Maui and Lanai have been described as "whale soup." But it remains to be seen whether this is a good idea at this time. Will keep you posted.
Whale watching in Maui is a MUST DO during Whale season (Dec thru Apr). There are numerous commercial whale watch companies leaving from Lahaina harbor but reservations are strongly recommended. You'll have a good time with any of them. We don't want to "push" any one firm, but here are some things to consider:
1. You want a boat that's not over crowded.
2. You want a boat which has a naturalist on board to give knowledgeable commentary about whales.
3. You want a boat that's fast enough to get to the whales if an active pod is a distance away.
4. You want a boat that's safe and comfortable.
5. Some boats have heads, some don't.
6. Some boats guarantee that you'll see whales. (free next trip, if you don't)
7. Keep the weather in mind. You should pick a day when the forecast is for no rain and calm seas.
8. How many whales you see, how active they are, and whether you see dolphins too is a matter of luck. Mornings, mid day and afternoons are all ok.
Some whale watches are 2 hours long and they're fine. Others are longer including snorkeling, lunch, seeing sea turtles, etc. take your pick.
I personally like Ultimate Whale Watch Maui. But they're all good.