Caroline Islands

Some of the islands are volcanic islands with coral reefs around them.

Others are low rings of coral that barely rise above the sea.

The islands of this part of the Pacific range from tiny coral atolls barely rising above the sea to volcanic high islands and raised limestone islands. Pohnpei and Kosrae are volcanic high islands with coral reefs along their shores.

Yap is different: the Smithsonian says its four islands are made of continental crust, lifted up from the Philippine Sea Plate and joined within one coral reef.

The Smithsonian describes Micronesia's geology as complex, with six distinct geological subregions. In the Carolines, Pohnpei (344 km², 772 m) and Kosrae (110 km², 634 m) are volcanic high islands with fringing coral reefs; Yap's four islands are continental crust, formed entirely from an uplift of the Philippine Sea Plate and joined within a common reef; and Chuuk Lagoon holds mountainous volcanic islands inside a barrier reef ringed with coral islets.

Palau mixes volcanic islands (Babeldaob, 331 km², 242 m), coral reefs and atolls, low platform islands and uplifted limestone islands.

In Palau, hundreds of rocky islands look like mushrooms.

They sit in bright blue-green water.

Palau's Rock Islands are a UNESCO World Heritage site. UNESCO says the site has 445 uninhabited limestone islands of volcanic origin, many shaped like mushrooms, in turquoise lagoons surrounded by coral reefs.

It also has more marine lakes than anywhere else: pools of seawater cut off from the ocean by land.

UNESCO's Rock Islands Southern Lagoon covers 100,200 ha with 445 uninhabited limestone islands of volcanic origin, many with mushroom-like shapes, in turquoise lagoons surrounded by coral reefs. The Smithsonian counts over 300 Rock Islands in central and southern Palau, many steep-sloped and mushroom-shaped.

UNESCO adds that the site holds the highest concentration of marine lakes anywhere, isolated bodies of seawater separated from the ocean by land barriers, whose high endemism continues to yield new species.

Many kinds of coral, fish and sharks live around the islands.

Some plants grow here and nowhere else.

UNESCO says the Rock Islands' reefs have over 385 kinds of coral, and the waters are home to dugongs and at least thirteen kinds of sharks.

On land, the Smithsonian notes that about 364 kinds of plants are found only in Micronesia, most of them in the Caroline Islands and many only in Palau.

UNESCO describes a complex reef system with over 385 coral species and a large diversity of plants, birds and marine life, including dugong and at least thirteen shark species.

The Smithsonian places Micronesia within the Polynesia-Micronesia biodiversity hotspot and cites an estimate of 364 vascular plant species endemic to Micronesia, most occurring in the Caroline Islands, with a large percentage restricted to Palau.

The islands are surrounded by the ocean.

Near water, always stay close to your grown-up and wear a life jacket on a boat.

The Caroline Islands are surrounded by the Pacific Ocean. The US Centers for Disease Control and Prevention (CDC) says life jackets lower the risk of drowning while boating, and that children should wear them for all activities in and around natural water.

Grown-ups should watch children closely whenever they are near water.

The CDC advises that life jackets reduce the risk of drowning while boating for people of all ages and swimming abilities, that children should use them for all activities in and around natural water, and that adults should supervise children closely even when lifeguards are present.