It is located in the region of Vila Nova de Gaia, municipality and district of Porto, Northern Portugal.
 
Piscina das Marés is located on Avenida da Liberdade, parish of Leça da Palmeira, Municipality of Matosinhos, District of Porto, Northern Portugal.

Piscina das Marés is a set of saltwater swimming pools located in Praia de Leça, Parish of Leça da Palmeira, Municipality of Matosinhos, District of Porto, Northern Portugal.

Piscina das Marés was built in the 1960s and opened in 1966, it was designed by architect Álvaro Siza Vieira, the most renowned and award-winning contemporary Portuguese architect.

Young Álvaro Siza Vieira, then 26 years old, was called to carry out a saltwater pool project on the shore of Leça da Palmeira, in Matosinhos.

The complex completed in 1966 consists of changing rooms, a café and two swimming pools: one for adults and one for children, and became one of its most recognized projects classified as a National Monument of Portugal in 2011.

The project takes advantage of the natural depressions in the rocky terrain to install the salt water tanks.

The pools reach the ocean and blend in with the other natural formations found along the coast of Matosinhos.

The volumes integrate with the landscape, hiding it and framing it at times but clearly demarcating human intervention on the natural site.

Architect Siza Vieira works with a purposeful contrast between the organicity of the stones and the accentuated geometry of the architecture.

The building is placed parallel to the road, below its level, leaving the horizon completely clear from the road.

The programs are accessed via a gentle ramp, which gradually obscures the views of traffic and the ocean, the transition between the road and the sea is marked as a sensorial experience during the journey the ocean becomes barely audible.

Leaving the changing rooms you enter a series of platforms, the water once again becomes the dominant view with the pools appearing between the vast ocean and the complex.

The pools, made up of low concrete walls with natural rock formations, are spread along the edges of the pools that blend into the ocean horizon.

Intentional blurring confuses the real understanding of the created limit and visually increases the extent of the space.

The complex was built in concrete with the shapes of horizontal wooden boards evident in the concreting, the tone of the concrete used is slightly lighter than the rocks on the ground, highlighting the action of man on the natural environment, the roofs are made of wood covered with copper sheets on asphalt sheets.

The building's 50th anniversary was celebrated with a restoration with simple interventions in the building that remains in use.

The book “Piscina na Praia de Leça – A Pool On The Beach” was launched with drawings, photographs, memories, as well as texts by Siza himself and other authors.

The Tidal Pools of Leça da Palmeira, by Álvaro Siza Vieira, completed 50 years on September 29, 2016.

The two saltwater swimming pools (one just for children) are an alternative to the various beaches that stretch throughout the municipality of Matosinhos, including two swimming pools, changing rooms and changing rooms and a bar/lounge.
The Classification of the Tidal Pool in Leça da Palmeira
 
In 2006, Piscina das Marés in Leça da Palmeira was classified as a National Monument.