The Whitsundays are built around boats. Day cruises run to Whitehaven Beach, scenic flights loop over the islands and outer reef, and overnight sailing trips spend their time moving between sheltered anchorages on Whitsunday Island, Hook Island, and smaller coves.
If you are short on time, choose one strong beach-and-snorkel trip rather than trying to see everything. With two or three days, a sailing trip gives the islands room to breathe: sunrise on deck, a snorkel before the day boats arrive, and a quiet anchorage after sunset.