The Olympic-size East Potomac Pool at Hains Point remains closed, but serious swimmers have other outdoor options. In Alexandria, the Old Town Pool offers multiple lap lanes on a first-come, first-served basis for residents and nonresidents in its 25-yard main pool. Over in Maryland, triathletes will appreciate that there are lanes in the Z-shaped, 50-meter-long main pool at Bethesda Outdoor Pool, and another six lanes in a separate dedicated lap pool. In D.C., try to snag one of the multiple lap lanes at the Harry Thomas Sr. Pool in Eckington.