My family and I (3 adults) visited Hamoa beach one afternoon during our 3 night stay in Hana in early December on the recommendation of the woman whose property we were renting. She couldn't have pointed us to a better location. It's relatively small, but at 2pm in the afternoon it was very lightly attended with plenty of space to stretch out. There is a lot of foliage and trees that ring the shore, which provides shade if you want to come in from the sun at any point. The water was very clear and relatively calm, and you can easily stay in for 30+ minutes without getting chilly. Aside from some plant debris, there was no seaweed, or shells and rocks in the water or at the shoreline. The sand is wonderful to dig your toes into; very fine and partially black with a grey gradient that fades closer to the water's edge.
Because the beach is secluded in a cove, the winds don't get to be more than a breeze. Later in the day there was some wave action for boogie boarders and body surfers though, but it's not a surfing beach. There were some cool rock jetty's to explore and, apparently, catch fish in. I ran into a local man who had done some diving in the rock crevasses and captured a lobster and octupus for dinner. It was quite a site seeming him come out of the water with his camo diving suit, spear gun, and catch strapped to his belt.
There is no parking lot up top, so be prepared to pull over and park on the curb in the brush. When you pull off Hana Highway, you'll also come across another beach first called Koki Beach. This does have a lot, however the surf is very rough here. Don't confuse the two. Hamoa is unmarked, but you'll see the cars hugging the shoulder and there will be a staircase and small bus stop at the entrance for shuttle vans to drop off nearby hotel goers. On the beach itself, there is also a restroom and a shower station to rinse off before you leave.
I had a wonderful time relaxing in the afternoon sun and taking a dip in the water. I highly recommend it!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC