The shallow warm waters between Maui, Lānaʻi, and Molokaʻi form the Hawaiian Islands Humpback Whale National Marine Sanctuary, and from December through May this is one of the best places on earth to watch humpback whales. At peak season, breaching, spy-hopping, and tail-slapping whales are visible from shore along the south Maui coast; on a boat you get close enough to hear them.
Whale watching boat trips depart from Ma'alaea Harbor and Lahaina. Most operators run two-hour tours with a marine naturalist who explains the behavioural patterns and plays hydrophone recordings of whale song through speakers. Pacific Whale Foundation, Trilogy, and Alii Nui are well-regarded operators. Many tours are catamaran-based and include snorkelling stops.
Even from a car, the coast between Maalaea and Wailea in February is productive — pull over at any lookout on South Kihei Road and scan the water. Binoculars help but are not essential during peak months.