Classroom lesson · To Sua Ocean Trench · 🇼🇸 Samoa

To Sua Ocean Trench

A magical deep blue swimming hole reached by a tall wooden ladder

Photo · Wikimedia Commons

What is it?

To Sua Ocean Trench is an enormous, perfectly round swimming hole on the island of Upolu in Samoa. It looks like a giant cup filled with the clearest blue-green water you have ever seen. To get in, you climb down a very long wooden ladder — and when you reach the bottom, you are swimming in water connected all the way to the Pacific Ocean.

Tell me more

'To Sua' means 'big hole' in Samoan — and that is exactly what it is! The hole is about 30 metres wide and more than 30 metres deep, carved out of black volcanic rock over thousands of years by waves and rain. Tropical gardens full of ferns and flowers grow around the rim.

The water is always a wonderful turquoise colour because it is actually connected to the sea through an underwater tunnel in the rock. This means that when the tide comes in, the water level inside rises too. Swimmers say it feels like floating inside a secret jewel.

To get into the water you climb down a long wooden ladder that is fixed to the side of the rock wall. Counting the steps as you go down is part of the adventure! At the bottom, there is a small ledge where you can jump into the pool. The water is warm because Samoa is close to the equator.

Around the trench there are lush tropical gardens with coconut palms and tropical flowers. Samoan families often bring a picnic to enjoy on the grass while the children take turns on the ladder. It is one of the most photographed places in the whole South Pacific.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

01How would you feel standing at the top of that long ladder looking down at the blue water? Would you climb down?
02The pool is connected to the sea underground — what other hidden connections can you think of in nature?
03Why do you think volcanic islands like Samoa have so many unusual rock formations?

Try this

Classroom activity

Draw a cross-section (a side view cut through the middle) of To Sua. Show the garden at the top, the rock walls going down, the wooden ladder, the pool of water, and the secret underwater tunnel leading to the ocean. Label each part and colour it in.

To Sua Ocean Trench

Walk your class through this in 15 minutes.

Discussion prompts

Classroom activity

Other things that make Samoa special

Want your class to meet Samoa?