Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
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Spain, a country on Europe?s Iberian Peninsula, includes 17 autonomous regions with diverse geography and cultures. Capital city Madrid is home to the Royal Palace and Prado museum, housing works by European masters. Segovia has a medieval castle (the Alcázar) and an intact Roman aqueduct. Catalonia?s capital, Barcelona, is defined by Antoni Gaudí?s whimsical modernist landmarks like the Sagrada Família church.

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