Surface Area
84 km²
Iceland's largest natural lake, fed by underground springs and rivers.
Þingvallavatn: Iceland's Largest Natural Lake
Iceland's largest natural lake at 84 km², in a rift valley within Þingvellir National Park. Home to the Silfra snorkeling fissure and four morphs of Arctic char.
Location
South Iceland
84 km² · Max depth 114 m · UNESCO World Heritage Site
Quick Answer
Þingvallavatn is Iceland's largest natural lake at 84 km², in a rift valley in Þingvellir National Park, with Silfra snorkeling and four morphs of Arctic char.
Þingvallavatn fills a rift valley created by the separation of the North American and Eurasian tectonic plates. The lake's clear water is filtered through underground lava fields over decades before reaching the basin. It lies within Þingvellir National Park, a UNESCO World Heritage Site and the place where Iceland's parliament (Alþingi) was founded in 930 AD. Today visitors come for Silfra's underwater visibility and for the rift landscape itself.
Sources and page update
Updated: 2026-09-10
This guide is a travel-planning summary, not emergency guidance. Conditions in Iceland can change quickly; check official alerts, roads, and weather before driving, hiking, or booking around volatile conditions.
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Top Activity
Silfra Snorkeling
Snorkel or dive between tectonic plates in water with 100m+ visibility.
Access
Year-Round
About 45 minutes from Reykjavik via Route 36. Golden Circle stop.
What to Expect
Silfra Fissure
Snorkel or dive between the North American and Eurasian tectonic plates in glacial water with visibility over 100 meters.
Tectonic Rift Valley
Walk along fissures and fault lines where the continents are slowly pulling apart at about 2 cm per year.
Arctic Char Diversity
Four genetically distinct morphs of Arctic char evolved in the lake after the last Ice Age, a phenomenon studied by biologists worldwide.
Historic Þingvellir
The lake sits below the site of the world's oldest existing parliament, founded by Viking settlers in 930 AD.
Fishing Opportunities
Licensed anglers can fish for brown trout and Arctic char in the areas and season specified by their permit.
Scenic Lakeshore Walks
Multiple trails along the northern and eastern shores offer views of the lake, surrounding mountains, and volcanic features.
Getting There
Þingvallavatn is about 45 minutes northeast of Reykjavik via Route 36. The lake is a core stop on the Golden Circle route, and the Þingvellir National Park visitor center on the north shore provides parking, restrooms, and information. Silfra snorkeling and diving tours typically meet at the Silfra parking area on the lake's northern edge. The road is paved and accessible year-round, though winter conditions may require caution.
Best Time to Visit
Þingvallavatn can be visited year-round. Summer (June to August) offers the longest daylight hours and warmest temperatures for lakeshore walks. Silfra snorkeling and diving operate throughout the year since water temperature remains constant at 2-4°C. Autumn brings golden colors to the surrounding birch and the chance for northern lights. Winter is stark and quiet, with fewer crowds. Spring sees the return of migratory birds to the lakeshore.
Fishing rules apply to a specific shore and season
For the national park fishing area, the park’s current rules list April 20–September 15, with fly-only fishing through May 31. A valid permit is required before fishing; the park permit excludes Kárastaðir.
Boats and floating devices are prohibited for angling in this area, and all catches must be recorded, including released fish. Follow the linked map for closed sections rather than treating a permit as access to every shore. These conditions were checked on September 10, 2026.
Planning help
Þingvallavatn FAQs
Quick answers with safety notes where it matters.
How big is Þingvallavatn?
Þingvallavatn covers approximately 84 square kilometers and is Iceland's largest natural lake. It reaches a maximum depth of about 114 meters.
Can you swim or snorkel in Þingvallavatn?
Yes. Silfra fissure, located in the lake's northern section within Þingvellir National Park, is one of the world's top snorkeling and diving sites. Visibility in the glacial water exceeds 100 meters, and the water temperature stays around 2-4°C year-round.
Is Þingvallavatn part of the Golden Circle?
Yes, the lake sits within Þingvellir National Park, which is one of the three stops on the Golden Circle route alongside Geysir and Gullfoss. Most visitors see the lake as part of a Golden Circle day tour from Reykjavik.
What fish live in Þingvallavatn?
The lake is home to four distinct morphs of Arctic char that evolved after the last Ice Age, which makes it a site of significant scientific interest. Brown trout and threespine stickleback also inhabit the lake. Fishing permits are available for anglers.
Country reference: Iceland statistics.