Banderas Bay is one of the largest bays in the Pacific and deep enough that humpback whales come into it to calve. From December to March they are often visible from the shoreline, and the whale-watching boats out of Marina Vallarta are among the more reliable in Mexico. Federal rules set approach distances and operators carry permits.
Los Arcos, at the southern end of the bay, is a national marine park: granite islets with sea arches worn through them, a shallow snorkelling side and a wall on the outside that drops past forty metres. The Islas Marietas, across the bay in Nayarit, are the other park — blue-footed boobies above water, a hidden beach inside a collapsed cave, and a hard daily visitor cap.
South of the city the coast has no road. Yelapa, Las Ánimas and Quimixto are reached by water taxi from Boca de Tomatlán, and the walk between the coves through the jungle is one of the better days here. Inland, the sierra has canopy tours, river walks and the old mining town of San Sebastián del Oeste up a mountain road.
Sport fishing out of the marina is serious — sailfish, marlin and dorado — and November's international tournament is the biggest of its kind on this coast.