Honolulu · With kids

Small enough to finish before a toddler melts, with monk seals, a reef tank and outdoor pools. Ages two to eight, an hour or two.

Fourteen acres at the Diamond Head end of Waikiki, walkable from most hotels. Under-eights do best; go early before the heat settles in.

A flooded crater with clear shallow water over reef. Reservations open online days ahead, the preserve closes two days a week, and confident paddlers from six upwards manage.

Four man-made coves on the leeward side with almost no swell, sand bottoms and lifeguards. Any age, and about as gentle as ocean swimming gets with small children.

Oxybenzone sunscreens are banned — bring mineral. Shade is scarce by ten, shave ice fixes most meltdowns, and restaurants fill early and empty by nine.