If you’re an adventurer who likes to explore off the beaten path, these unique seaside caves should be on your to-visit list.

Across the globe, there are some incredible caves that will reward brave explorers ... but only those who are willing to take the time and effort to get to them. These out-of-the-way seaside caves are gorgeous, but they can be reached only by boat:

1. Cathedral Cove, New Zealand

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This might be one of the most postcard-worthy sea cave clusters in the world. It features a nature-forged archway, clear water and a shimmering sandy beach. If it looks familiar, maybe you remember it from “The Chronicles of Narnia: Prince Caspian.”

The cove has several caves, but they are accessible only by boat or on foot. You can take a tour or hire a kayak to get there.

2. Great Blue Hole, Belize

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The Great Blue Hole is quite something to see. But you’re going to have to approach it by sea. You'll need to scuba dive to appreciate its beauty.

Great Blue Hole is a gigantic sinkhole off the coast of Belize. It’s 400 feet deep, and within its caverns you’ll find large-scale stalactites and some spectacular formations of coral. The clear waters make it easy to see the beauty of this massive natural formation as well as the area’s marine life, including sharks and tropical fish.

3. Grotta Azzurra, Italy

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Translated as “Blue Grotto,” this cave seems like something from a storybook. It has a narrow entry, so you’ll pass through an area of pitch black before being led into a cavern that seems to sparkle and glow in a deep azure blue. It’s considered a must-see in the Capri area.

The amount of tourists who flock to Grotta Azzurra is a testament to how incredible it is to behold. This is especially true because it’s not easy to get to. It requires taking a boat from nearby Capri Island. Plenty of tours are available, or you can hire a private boat and commission a rowboat to get into the tiny entrance.

4. Marble Cathedral, Chile

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In Patagonia, there’s an incredible cathedral to see ... but it’s not a church in the traditional sense. This is a work of natural wonder composed of many caverns of marble positioned over General Carrera Lake, one of the largest freshwater lakes in Chile. The natural texture of the marble reflects the water below in a stunning way.

When the water levels are low enough, it’s possible to get through some of the passages to explore, but only via boat or kayak.

5. Pak Ou Caves, Laos

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Close to where the Ou River meets the Mekong River, you’ll find the Pak Ou Caves. It’s actually two caves, both of which have been considered places of worship for many years.

In the caves, you’ll find thousands of Buddha sculptures within a moody setting (candles are the primary lighting). Boat operators can take tourists to the caves. Feel like stopping for drinks? Why not? There’s a whiskey bar along the way back to dry land.

6. Raja Ampat Islands, Indonesia

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Located in the Raja Ampat archipelago, this series of more than 1500 islands offer an incredible glimpse of natural beauty and marine biodiversity.

The area is accessible only by boat, but plenty of adventurous travelers are willing to make the journey to see the eerie caves, incredible coves, and unique animal life. It’s long been a destination for accomplished divers, too.