Take your swimsuit to Oasis Waterworks (6321 W. Canal Dr., Kennewick, 509/735-8442, daily in summer) and try its 10 water slides, a “rolling rapids river ride,” 5,000-square-foot swimming pool, shaded picnic area, 100-person hot tub, and more.
Rent pontoon boats at Columbia Park Marina (1776 Columbia Dr. SE, Richland, 509/783-1649).