Gov. Code 831.7 immunizes governmental entities from liability for any injury arising out of a hazardous recreational activity. This decision holds that unlike Gov. Code 846 which applies only to premises liability claims, section 831.7 more broadly immunizes government entities from claims whether for hazardous conditions of property or employee negligence in connection with hazardous recreational activities. The decision also holds, however, that Harbors and Navigation Code 655.2 applies to boats operated by cities (though not by counties or other parts of state government), setting a 5 mph speed limit on operation of the vessels when within 100 feet of a bather or 200 feet of a beach used by bathers. The trial court erred in failing to instruct the jury on this basic speed law at plaintiff’s request in connection with his suit for injuries he suffered when a city employee on a jet ski passed him on his surfboard and then turned and cut in front of him. The basic speed law is relevant to the issue of gross negligence (an exception to 831.7 immunity) as well as to the more normal negligence per se issue.