The Keanae Peninsula is about halfway along the Hana Highway, formed when a zillion cubic feet of lava blew out the west side of Haleakala's Ko'olau Gap and fanned into the ocean. Although on this day rain made the conditions less than ideal, Keanae serves up to spots to take a dip in fresh water:
Shown below is near the village where the stream flows along the cliff and meets the river at a gravel bar, forming the Keanae Pool. It's huge.
The second spot, known as Sapphire Pools, is hiding in plain site just below the highway at the turnoff to the village. You need to climb down to it, but the trail is not bad. A deep pocket of bedrock makes for clean, clear water, even on a day like this. When the sun make a direct hit, the water is sapphire blue.
If swimming is not in the cards, be sure to take a stroll around the Keanae Arboretum, a freebie just off the highway a mile before the village turnoff. Exotic trees plus a Polynesian garden await. The seascape at the shoreline in Keanae is wild, where statuesque columns of jagged lava take on breaking waves.