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Need to know




The Mermaid Caves are one of Oahu’s best kept secrets (partly because locals usually won’t tell tourists how to find them). Hidden below a hollowed out lava rock is an underwater grotto with turquoise blue waters that reflect off the walls. 


They are incredibly beautiful and enchanting but can also be dangerous. There are plaques outside the cave with the names of people who have lost their lives here. Be sure to read the Tips + Tricks section for safety precautions. At the very least, don’t attempt to go alone or at high tide. 


If you’re there at low tide on a day when the waters are calm, you can drop down inside to explore. FYI that you’ll need some upper body strength or a boost from a friend to pull yourself back out. But even if you don’t go inside, it’s cool to look through the pukas (holes in the lava rock) to see the scene below. 


And bonus, the surrounding beaches are really nice and way less crowded than others — with restrooms and playgrounds nearby.


Head to Nanakuli Beach Park. (Google Maps will get you there.)

  • If you’re facing the ocean, head to your left and walk towards the lava rocks.

  • It’s about a 5-7 minute walk to the cave.

  • Google Maps added a handy camera icon to mark the spot. 




  • Electric Beach — 4 min drive

  • Paradise Cove Luau — 5 min drive

  • Monkeypod Kitchen — 8 min drive

  • Ka’aha’aina Cafe — 12 min drive​

  • Aloha Poke Shop — 15 min drive

  • Waikiki — 45 min drive

A secret underwater grotto, hidden below a hollowed out lava rock. Enchanting but can be dangerous — don’t go alone or at high tide. Read on for more safety tips.

Mermaid Caves


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Good to know





  • Rubber soled water shoes. You’ll have to walk on some jagged lava rocks and drop down into the cave lined with little rocks and ___ which will scrape up bare feet. 

  • Travel First Aid Kit for any scrapes you get trying to drop down into the cave or pull yourself back out. 



  • Restrooms at the surrounding beaches.

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  • It’s dangerous so follow all safety tips. There are plaques outside the cave with the names of people who have lost their lives here.

  • Only visit the Mermaid Caves during low tide and when the water is calm. You can check the tides here. The water level inside the cave changes with the tides, so if you’re in the cave when a swell hits, the cave can fill suddenly — you can be smashed into the rocks or pulled out to sea. During high tide, the water level comes up as high as the holes at the top of the cave. 

  • Summer (May - Oct) is the best time to visit because the waves tend to be less rough and the water levels lower. 

  • Don’t go in alone. It’s important to have other people there with you in case you run into trouble. If you go into the cave, don’t venture too far away from each other.

  • Getting into the cave. Lots of people enter the cave by jumping through the big holes in the rock. Keep in mind there’s a pretty long drop (about 8 feet). Don’t attempt this without rubber sole water shoes. Another (safer) route is to head to the back of the rock (towards the street) and drop down about 8 feet onto the sand below. 

  • Before you go in, make sure you can get back out. You’ll have to use your upper body strength to pull yourself back up to the top (about 8 feet). There are a few crevices in the rock to help you, but you definitely need to be fit enough to get yourself out. Another good reason to go with friends in case you need a boost or helping hand to get out. If you’re really lucky, you may be there on a day when a local brings a ladder or a rope, but don’t count on it.

  • Wear water shoes with rubber soles. Bare feet will get scraped up walking along the jagged lava rocks to get to the caves. Keep your water shoes on to jump into the cave because you’re going to land on crushed coral and rocks. Bare feet and flip flops are a bad idea. 

  • Don’t venture too far into the cave and pay attention to changes in the water level. As soon as you make your way into the cave, you’ll be surrounded by the beauty of this mystical place. You really don’t have to wander far. Keep track of time and the tides and stay close to your friends. 

  • Don’t try to swim out of the caves against the current. It’s extremely dangerous, even for strong swimmers. 

  • You don’t have to go into the cave. From the outside you can peek into the holes to get a look at the beauty below and it’s fun to see people exploring down there. 

  • The nearby beaches (Zablan Beach and Nanakuli Beach Park) are beautiful and less crowded than others. Whether you go into the cave or not, these beaches are still worth visiting. There are restrooms, a large grassy area, and a playground. 



  • There are no lifeguards and the water currents can get strong.

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  • This is not a kid friendly activity. The water can be dangerous. You also have to drop about 8 feet to get into the cave and should be able to pull yourself back out.

  • The surrounding beaches are kid friendly, although no lifeguard.

  • There’s a playground nearby.



  • The Mermaid Cave is actually a large lava rock that’s been hollowed out over time by the ocean’s waves.

  • There’s a rumor that it got its name because there were half fish, half human creatures that used to visit the cave when the moon was high

Last Updated 9 / 17 / 21

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