• The mesmerising pool, almost 100ft down, is on the volcanic island of Upolu in Samoa
  • Visitors can enjoy crystal-clear waters populated with tropical fish and a sandy bed
  • A steep ladder leads down to the water, with tourists using it to dive into the pool 

This natural swimming pool on a volcanic Samoan island offers visitors the ultimate experience in relaxation.

To Sua Ocean Trench, which literally translates as 'big hole,' is located in Lotofaga village, on the south coast of Upolu island in Samoa. When the volcanoes erupted on the island, much of the ground fell away, and this 98-foot deep hole was the result.

Steps lead down to a ladder, which tourists can use to descend into the grotto, or use as an impromptu diving board (providing the water levels are high enough).

For those less brave, a tumble in from a board a matter of inches above the water may be the safer option.

The To Sua Ocean Trench on the Samoan island of Upolu offers swimmers a truly unique and unforgettable experience

The green landscape is matched by crystal clear waters, an abundance of tropical fish and a sandy bed. A series of canals leading from the pool to the South Pacific Ocean ensure the hole is never dried out.

In order to protect the serene spot, as well as maintain the safety of the visitor routes into the water, there is a charge to swim. It will cost adults £10 ($15), children £3.85 ($6.00), but is free to those under the age of seven.

The beauty of Samoan spot has not been lost on most who have visited it.

Writing on TripAdvisor, Georgie P from Brisbane, Australia says: 'To Sua is one of the most unique, relaxing places I have been to. When I went there was only one other couple there so it was very peaceful.

Craig02128 adds: 'A magical experience, swimming at the bottom of the grotto. If you are a strong swimmer, you can even swim underneath the rock tunnel and out to the ocean.

'We visited the trench in May and absolutely loved it, the place is so beautiful and the water is warm and clear. Recommend visiting this paradise on earth,' writes Andrea R.

The pool is maintained by water flowing in from the South Pacific Ocean through a number of channels and tunnels

Visitors to the trench are warned to take care when walking down the ladder, as expectedly, it can become slippery.

CJB1985 adds on TripAdvisor: 'The climb down looks bad but if you take your time and wear sandals it's ok.'

The review website has scored To Sua Ocean Trench a four-and-a-half rating out of five based on visitors' reviews. Of the 401 people to have commented on the tourist attraction, 319 have rated it as 'excellent.'

Other stunning natural swimming pools around the world include Iceland's famed Blue Lagoon geothermal spa and the travertine pools and terraces in Pamukkale, Turkey.

The beautiful swimming pool is found on the volcanic island of Upolu, belonging to Samoa and located in the South Pacific Ocean

In Pammukkale, Turkey, the travertine terraces have become hot springs, where people have bathed for thousands of years

In Luang Prabang in Laos, tourists flock to the gorgeous pools and flowing water in the Tat Kuang Si waterfall system

Near Chichen Itza in Mexico, the breathtaking Ik Kil cenote attracts many visitors, as it's located in an archeological park

One of the most visited attractions in Iceland is the Blue Lagoon geothermal spa, located on a lava field in the Reykjanes peninsula