Mermaid Cave / Tunnels

4.5 stars from 6 reviews
Address 416 Keaulana Ave, Waianae, HI 96792
Potentially dangerous but beautiful water cave near Nanakuli Beach Park.

• General: Cost: Free • General: Photo Opportunity
• Hiking: Level: Difficult • Hiking: Rock Climbing

Full Description
Mermaid Cave, or tunnels as it's often called, has grown in popularity in recent times. But this is strictly for the adventurous few seeking to experience a hidden treasure in Hawaii. Mermaid Cave is located at Nanakuli Beach Park / Nanakuli Community Park / Kalaniana'ole Beach Park. To get there, you'll cross jagged lava rock that could cut up your feet, descend through an open hole (or puka) below into a breathtaking underwater cave.

However, just like any activity in Hawaii, you need to be careful. Exploring any cave, especially a wet cave, is incredibly dangerous and not for most people to attempt. The water level in the cave will change with the tides but can also fill suddenly with any large swell.

If you decide to enter the cave, something we do not recommend, then it should only be done during low tide and calm water. The cave fills and drains with the surge of the tide. Do NOT attempt this in a surging swell. When you're ready to get out, you'll need to be able to lift your own bodyweight to get out through the puka. Some people require help and pulled up by friends, just one more reason to seek adventures and do your exploring with friends.

Mermaid Cave is an adventure. It's beautiful, relatively hidden, and potentially lethal if you're not careful. Check it out from the outside instead or try one of the many other Oahu activities that are less dangerous.

Joined: Aug 2017
Reviews: 1
Likes Received: 0
As a resident of that community, I would highly suggest that all people stay out of the tunnels. It is not safe especially during high tide. My cousin recently risked her own life to save a visitor a few weeks ago. He jumped in, got knocked out face down on the reef with his wife and child on top screaming in terror. My cousin pulled him up and out of the water unconscious and did C{R where he gained consciousness.

If she didn't hear them, he would've died. It is not a safe place to swim if you don't know the area. Luckily the man survived while my cousin now needed to drive herself to the ER and needed 10 stitches on her knee as the reef slit it open. Please please stay out of the tunnels. You may not be as lucky as the man was. Just saying.
Jack W
Joined: Oct 2016
Reviews: 1
Likes Received: 1
4 Stars because it was high tide. It's a little difficult to find and you have to be looking for the entrance of the cave while avoiding tripping over the lava rocks. Once there you have to lower yourself into the cave, so be prepared for that as it's slippery and jagged.

Once down there it's a tight fight and you have to watch your head at all times. Be careful of the tide waves because they come rushing in the cave with great force and can knock you down. Other than that it's a great little adventure place, nice picture taking opportunity.
Tom T
Joined: Sep 2013
Reviews: 579
Likes Received: 33
At first, the Mermaid Cave reminded me of The Pirates of the Caribbean at Disneyland. It feels like a mini pirate cave. The way the light reflects off the water is so beautiful; it's something that would certainly inspire Disney's Imagineers.

Going into the cave is easy enough, but it was hard to climb out. There were about a half dozen people in the cave on my visit - all young, local, agile, not afraid of water, and could easily drop down and climb up without a problem. I, on the other hand, scraped my knee climbing out. There was another couple who dropped into the cave and needed assistance climbing out. If it was late in the day and we weren't around - who knows if this would have ended badly.

The Mermaid Cave isn't for everyone, but for those that can, it's worth checking out on a calm day with a low tide.
Mercy K
Joined: Jul 2016
Reviews: 1
Likes Received: 0
First thing first it's not called Mermaid Cave. It's called Tunnels. It's so beautiful. I grew up and live in the area my whole life.
Joined: Mar 2016
Reviews: 426
Likes Received: 12
Mermaid cave was absolutely breathtaking the views and crystal clear waters were magnificent! We were told to be very careful you need to go at low tide and we were safe. Highly recommended to anyone who loves an adventure. But be safe. Great photo opportunities the views are amazing. Would definitely go back again. You must check it out Mermaid cave!
Joined: May 2016
Reviews: 2
Likes Received: 0
When I went it was low tide, but still absolutely beautiful. Mermaid caves is right off Nanakuli Beach Park and it's actually inside the ground. The rocks have huge holes inside them and you simply jump through the holes and you see beautiful clear waters. You can stay as long as you want and when you're ready to leave you need to climb out using the rocks around you. It's definitely a place worth going to.
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