A coastal home to significant U.S. Navy installations, and sharing a border with Mexico, San Diego incorporates the sea and Mexican culture into its trademark Californian vibes. This premier alternative and extreme sports destination transcends land, air and sea, with street luging, paragliding and surfing just some of the adrenaline-packed activities you can enjoy in the San Diego sunshine, but there's also plenty that enthrals within Balboa Park's cultural sprawl.