- What it is: Costa Rica’s largest lake (85 square kilometers) and the reservoir behind the country’s most important hydroelectric dam, framed by Arenal Volcano and the Tilarán Mountains.
- Cost: Free to view, photograph, and swim. Boat tours, fishing trips, and water-sports rentals are paid separately.
- Hours: The lake itself is open 24/7. Public viewpoints along Route 142 are always accessible.
- Location: Northern highlands of Costa Rica, between La Fortuna and Nuevo Arenal. About 15–20 minutes from downtown La Fortuna via Route 142.
- Best for: Photography, windsurfing, kayaking, fishing, scenic drives, and anyone who wants a quieter side of the Arenal region.
The Story Behind Lake Arenal (And the Towns Under the Water)
Lake Arenal wasn’t always this big. The original lake was a small natural body of water that had existed in the valley for millions of years, fed by rivers flowing down from the Tilarán Mountains. Archaeologists have found pottery fragments along its ancient shoreline dating back to 1500 BC, making this one of the oldest continuously inhabited zones in the country.
Everything changed in the 1970s. Facing the global oil crisis, the Costa Rican government built the Sangregado Dam at the southeastern end of the valley through ICE, the national electricity institute. When construction finished in 1979, the lake had tripled in size. Two towns, Arenal and Tronadora, were submerged. Over 2,500 residents were relocated to what’s now called Nuevo Arenal on higher ground along the north shore. On exceptionally dry years, when water levels drop, you can sometimes spot the remains of the old towns poking through the surface.
The tradeoff reshaped the country. At its peak the Arenal Hydroelectric Project generated around 70% of Costa Rica’s electricity, helping launch the country’s reputation as a global leader in renewable energy. The lake you see today is, in a very real sense, the engine behind Costa Rica’s green ethos.
What to See & Do at Lake Arenal
How you experience the lake depends on which side you explore.
- Scenic drive along Route 142. The road runs along the northern shore from La Fortuna to Nuevo Arenal and delivers one pull-off after another, each with a different angle on the volcano and water. Plan at least two hours if you want to stop properly.
- Windsurfing and kitesurfing. From November through April, steady trade winds funnel across the western end of the lake, making it one of the top freshwater windsurfing destinations in the world. Rental shops operate out of the Tilarán side.
- Kayaking and paddleboarding. The eastern end near the dam is calmer and better suited for paddle sports.
- Fishing for rainbow bass and machaca. The lake is famous among sport fishermen for the fierce, colorful rainbow bass (guapote), found almost nowhere else. Half-day guided trips are widely available.
- Boat crossings to Monteverde. The jeep-boat-jeep transfer between Arenal and Monteverde cuts driving time roughly in half and delivers views you can’t get from the road.
- Wildlife watching. Over 100 mammal species and roughly 300 bird species live around the lake, including howler and capuchin monkeys, coatis, toucans, and ospreys.
Planning your first trip to Arenal? We can help you put the pieces together. From private shuttles to guided day trips, we design trips that go beyond the standard tourist loop and show you the Costa Rica we’d take our own friends to see.
Pura Vida!
