This high-clearance 4WD road crosses enough loose ʻaʻa (rough, jagged lava) to shake your fillings loose. Once only for adventurers, these remote black- and green-sand beaches with looming cliffs are no longer human-free pockets. You may find, after all the trouble of getting here, that the sea is too rough to swim and the beach too windy to enjoy. Even so, it's worth the trip for the scenery alone.
To find the Road to the Sea, turn makai off Hwy 11 at the row of mailboxes between mile markers 79 and 80 (look for the 'Taki Mana/Ka Ulu Malu Shady Grove Farm' sign). From there you'll drive 6 miles over rudimentary, seemingly never-ending lava. To reach the first and smaller of the two beaches at the road's end takes 45 minutes or so, depending on how rough you like your ride.
To reach the second beach, drive a half-mile back inland. Skip the first left fork (it's a dead end) and take the second left fork instead. Look for arrows painted on lava rock. The road jogs inland before heading toward the shore again, and the route isn't always readily apparent. There are many places you can lose traction or get lost. Almost a mile from the fork, you'll reach a red puʻu (hill). Park here and walk down to the ocean. You can hike the whole distance to the second beach from the split in the road, it's about 1.5 miles each way. Bring as much water as you can carry, because it's a mercilessly hot and shadeless walk.