Fodor's Expert Review Ullum Dam
Fifteen km (9 miles) west of San Juan, this huge hydroelectric complex—also known as the Ullum Valley Dam Reservoir—offers grand views of the Río San Juan. Windsurfing, sailing, swimming, rowing, fishing, and diving keep San Juaninos cool on hot summer days. You can rent boating equipment just beyond the dam, where you'll also find a café and change cabins. There's a public beach at the Embarcadero turnoff. You can go white-water rafting and kayaking on the San Juan, Los Patos, and Jachal rivers. Fly fishing, mostly for trout, in Las Hornillas River can be arranged through local tour companies.