Public transportation in the San Francisco Bay Area is quite extensive, including one heavy rail/commuter rail system, one commuter rail line, two light rail systems, Amtrak inter-city rail service, and four major overlapping bus agencies, in addition to dozens of smaller ones. In addition to rail and bus systems, there are multiple public and private ferry services, such as Golden Gate Ferry, which are being expanded by the San Francisco Bay Water Transit Authority. Most of the larger agencies accept the Clipper Card, a reloadable contactless smart card, as a universal electronic payment system.