Covering more than 4,600 acres split roughly evenly between land and water, Mission Bay Park is the largest man-made aquatic park in the United States, located within San Diego's 92109 ZIP code. The park traces its origins to a vast tidal marsh that Spanish explorer Juan Rodriguez Cabrillo named False Bay when he encountered it in 1542. Beginning in 1944, civic leaders launched an ambitious dredging project that moved 25 million cubic yards of sand and silt, transforming the wetlands into the recreational waterway that exists today. Water sports outfitters like Fastlane Sailing and Kayaking Center offer rentals and lessons for every skill level along the shoreline. The result of that mid-century transformation is 27 miles of shoreline, 19 miles of sandy beaches, eight designated swimming areas, and close to 14 miles of paved bike paths that wind past playgrounds, basketball courts, volleyball nets, and fire rings. On the water, visitors sail, jet ski, waterski, kayak, paddleboard, and fish, while on land, the park draws an estimated 15 million visitors each year for picnicking, running, and cycling. A nature reserve at the northern end near Crown Point preserves the Kendall Frost Mission Bay Marsh, home to endangered species including the light-footed Ridgway's rail and Belding's savannah sparrow. SeaWorld San Diego sits on the southern shore, and the Bahia Belle sternwheeler cruises the bay with live music on evening runs. Overnight stays along the bay are available at waterfront properties like Bahia Resort Hotel, which sits on the western shore. Free and paid parking lots are scattered throughout the park, though they fill quickly on summer weekends.