To Sua Ocean Trench is a 30-meter deep swimming hole filled with crystal clear salt water, surrounded by lush jungle hanging down the edges of the trench. To Sua is one of the most unique places to swim in on the planet, and going here is an absolute must if you’re visiting Samoa.
To Sua literally means ‘Giant Swimming Hole’. This Samoan water hole was formed by a cave-in of an ancient lava tube system that connects to the ocean, and thousands of years of erosion made it into the unbelievably beautiful spot it is now.
An underground cave system connects the swimming hole to the ocean, and the hole is accessed by climbing down a wooden ladder. Despite its size, To Sua is pretty much hidden from sight as you approach it from the entrance of the park.
The water in the trench is warm and full of fish, snorkeling is the best choice and you’ll be able to see heaps of colorful wildlife. Depending on the tide there can be a bit of a current in the trench. It wasn’t strong enough to drag us, but if that makes you feel uncomfortable there are ropes in the water to hold on to.
The western side of the ocean trench opens onto a small, sandy beach only accessible through a cave-like nook. Sheer rock faces of volcanic basalt disappear underfoot, leaving an epic ladder as the sole access point to the water below.
According to the Internet