The Hidden or Lovers Beach in Los Islas Marietas National Park off the coast is a beach in a crater created by bombing exercises in the early 1900s and reached through a short tunnel from the sea. The Marietas Islands, often called the Mexican Galapagos, have been a UNESCO Biosphere Reserve since 2008. They are a prime viewing area for humpback whales during the winter breeding season and excellent year around for snorkeling and bird-watching, including several endangered species. The boat tours from Puerto Vallarta are popular, so book early.