The site of the annual U.S. Open Sand Castle Building Contest, Imperial Beach draws hundreds of thousands of spectators and competitors from around the world each July. The creations range from fairytale castles to science-fiction landscapes to fantasy mermaids and other inspired forms. The party lasts all weekend, with a street fair on Saturday and main event on Sunday, but its fruits do not. Inevitably, the tide comes in and washes the beach clean again.
Along the residential strip lining the long beaches of Imperial Beach, surfing, body boarding and swimming are good and popular activities throughout the summer. Tijuana Sloughs and Border Park are the large and largely impassible marsh areas south of Imperial Beach Blvd. The estuarine lagoons and river mouths here comprise a National Wildlife Refuge of special interest to bird-watching enthusiasts, and the parks service offers guided nature hikes and visitor information. Aside from their environmental appeal, the beaches here offer little and swimming is not recommended.