An atoll forms when a volcano that once poked up above the sea slowly sinks back down over millions of years. The coral reef that grew around it is left behind, making a ring of low-lying land. Tarawa's highest point is only about three metres above sea level, which means the ocean is never far away - you are never more than a short walk from the water on either side.
The lagoon inside Tarawa's ring is calm and sheltered, so it is perfect for fishing, swimming, and sailing small boats. Local children learn to swim very young, and many families keep canoes called te wa that they use every day. The lagoon is also full of colourful fish, and people catch fresh fish for meals just as easily as going to a shop.
South Tarawa is the busiest part, where the government buildings, markets, and schools are. Families travel between the islands of the atoll by driving across narrow causeways - roads built just above the water that connect the little islets together. It feels a bit like driving across a bridge that never quite ends.