Land of the Lost 2

Rick Marshall is a park ranger who takes his two kids, Will and Holly, on a rafting trip down a river. During the trip, an earthquake occurs which somehow opens up a rift in time, propelling the Marshalls into a land populated by dinosaurs, ape-men, and the dreaded Sleestak. Later in the series, Rick manages to find his way home and is replaced by Uncle Jack (who had rafted down the same river looking for his family).