In the summer, with calm seas there is a pool to swim in on a lava shelf with an inlet to the sea. In the winter do not go (many people have drowned here). Even in the summer only go in calm seas and watch for rogue waves.
Follow the sometimes slippery trail 120 feet down to the beach then turn left along the lava.
Don’t be an idiot – if there is anything other than calm ocean find somewhere else and trail at your own risk. Check the surf report – anything more than 4 feet and you can’t go.