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These Natural Swimming Pools Were Formed by Lava

The picturesque islands of the Madeira archipelago were formed by millennia of volcanic eruptions.

Off the shore of the village of Porto Moniz on the northwestern coast of Portugal’s Madeira Island, swimmers float in a network of crystal clear seawater pools that reflect the azure of the sky.

The tranquility of the natural salt pools belies their violent creation story. The islands of the Madeira archipelago, southwest of mainland Portugal, were formed by volcanic eruptions on a large hotspot under the eastern Atlantic Ocean. Lava first reached the surface more than five million years ago, with periodic eruptions continuing until about 25,000 years ago.

The eruptions—along with erosion during the dormant periods—shaped Madeira’s steep mountains and valleys. During the most recent phase of volcanic activity in the last million years, lava flowed down through an existing valley and out to sea where Porto Moniz is today, cooling and hardening into the volcanic rock that now forms the walls of the pools.

Ocean water flows over the rocks and replenishes the pools—sometimes carrying fish and shrimp with it. High winds can send waves crashing over the rock barriers, but in calm weather, the pools offer a serene bathing experience for those who prefer to take an ocean dip without battling the breakers. The complex also includes a children’s pool and play area and is accessible for people with disabilities.

On shore, bathers will find all the amenities for a comfortable beach experience, including parking, changing rooms and lockers, a snack bar, and lounge chairs and sunshades for rent. Lifeguards are on duty, and there is a first aid station on site.

Porto Moniz also hosts a small aquarium and hikers can trek inland on the verdant Levada da Ribiera da Janela path.

As for the volcanoes that created this island paradise, there could be more to come. In the past, quiet periods between eruptions in the area stretched as long as 500,000 years. It’s possible that the next island is waiting to break through the ocean’s surface and join the archipelago.

Abby Sewell is a freelance journalist based in Beirut covering politics, travel, and culture. Follow her on Twitter at @sewella.

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