Shearwater offers plenty of tours, but its whale-watching excursion is the flagship trip. The six-hour adventure on a 47-foot catamaran leaves from the Town Pier. You’ll head out to look for humpback, finback, and minke whales, accompanied by a naturalist who will talk about the island, whales, and wildlife. The family-owned-and-operated business started in 1999 and is named for owner Captain Blair Perkins’s favorite bird, the shearwater. Another whale-focused excursion is the Whaling History Tour, where you’ll see landmarks from the Nantucket whaling era and learn about life aboard the whaleship Essex, featured in the film In the Heart of the Sea by Nantucket author Nathaniel Philbrick.