Lac de Trémelin: swimming, lake loop and activities

A lake of about 50 hectares in an estate of forest and heathland 30 minutes from Rennes: an accessible 5 km loop, a Blue Flag beach lifeguarded in summer, tree-top adventure and kayaking. Free entry.

Suggested time: 2 hours for the lake loop, a full day with children
Type of place: Lake, forest and leisure centre on the edge of Brocéliande
Atmosphere: Family-friendly and lively in summer, peaceful and wooded early in the morning and out of season
Getting there: Domaine de Trémelin, Iffendic, 30 to 40 minutes from Rennes: via the RN12, exit Montfort-sur-Meu / Bédée / Pleumeleuc, or via the RN24, exit Plélan-le-Grand, then follow Iffendic and Trémelin. Car parks P1, P2 and P3, often full from 12.30 pm on summer Sundays. No bus goes directly to the lake: Montfort-sur-Meu station or BreizhGo line 502 to Iffendic, then bike, taxi or car-sharing. Free entry to the estate and the beach.

Who this place suits

With family: 10/10
As a couple: 8/10
With friends: 9/10
Solo: 9/10
With a dog: 8/10
Reduced mobility: 8/10

These scores are calculated from what the page records: official rating, facilities, difficulty, duration and location. They are a guide, not a substitute for contacting the venue, especially about accessibility.

About

The Lac de Trémelin, officially the Étang de Trémelin, covers about 50 hectares in Iffendic, some thirty minutes west of Rennes, on the edge of Brocéliande. Around the water, the estate covers more than 220 hectares of forest, heathland and wooded shores, freely and openly accessible all year round. It is one of the busiest leisure sites in Ille-et-Vilaine, with more than 450,000 visitors a year. The essential walk is the loop around the lake, about 5 km in 1 hour to 1 h 30, almost always along the water and largely shaded. Easy, it is described as accessible to wheelchairs and pushchairs, which is rare around Brocéliande. Bikes ride at walking pace, pedestrians have priority, and horses have their own trails. To go further, the “Lac et Landiers de Trémelin” loop (10 km) climbs into the heathland towards the Chambre au Loup valley, and the “Balade des Deux Étangs” (11 km) reaches the Careil estate and its birds. Beyond the leisure centre, the lake has real natural value. It is listed as a natural area of ecological interest (ZNIEFF type 1) for its nutrient-poor waters and its shoreline flora: floating water-plantain, a small aquatic plant protected in France and of European interest, pillwort, a discreet aquatic fern, shoreweed and royal fern. Nightjars hunt over the heathland at dusk. Two invasive species, a South African aquatic plant and the red swamp crayfish, are being monitored. In summer, the Blue Flag beach welcomes swimmers, lifeguarded and limited to a marked area: in 2026, from 27 June to 31 August, 1.30 pm to 7 pm, with a floating wheelchair lent free of charge. Outside these dates and hours, swimming is forbidden. From April to September, the Aventur’O Lac centre rents pedal boats, canoes and kayaks, and offers tree-top adventure courses from age 3 and zip lines over 200 metres long. Anglers come for pike, zander and above all big carp, with a fishing permit. By the water, opposite the restaurant, a sword set in a rock is a reminder that Brocéliande is close by: it is a replica of Excalibur, the sword that, depending on the version of the legend, Arthur pulls from the stone or receives from the Lady of the Lake. The estate also has L’aparté, a free contemporary art venue opened in 2010, a tourist office, a restaurant, a campsite, gîtes and a small motorhome area.

What you will see

A lake of about 50 hectares in an estate of more than 220 hectares of forest and heathland, freely accessible all year round.
A 5 km loop around the lake, easy and shaded, described as accessible by wheelchair and pushchair.
A Blue Flag beach, lifeguarded swimming in summer and a floating wheelchair lent free of charge.
A lake listed as a ZNIEFF for its rare flora, including floating water-plantain, protected in France.
Tree-top adventure from age 3, zip lines over 200 m long, pedal boats, canoes and kayaks to rent from April to September.
The replica of Excalibur set in a rock by the water, best photographed at sunrise.

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L’aparté, a free contemporary art venue by the lake, with exhibitions and outdoor works.
A lake known for carp, pike and zander fishing.
Hikes to the heathland, the Chambre au Loup valley and the Careil estate, with the GR37 close by.
Tourist office, restaurant, campsite, gîtes and motorhome area on site.

Practical information

Address: Domaine de Trémelin, 35750 Iffendic
Public transport: No bus to the lake. Montfort-sur-Meu station; BreizhGo 502 Rennes-Gaël to Iffendic
Parking: Car parks P1, P2 and P3. Full from 12.30 pm on some summer Sundays. Parking outside marked areas is forbidden
Pets: On a lead on the estate. Not allowed on the beach or in the swimming area
Accessibility: The lake loop is described as accessible by wheelchair and pushchair. The beach is accessible, with a free floating wheelchair during lifeguard hours. The tourist office and L’aparté are accessible
Best time: May, June and September for peace and quiet; July and August for swimming and activities; autumn for the colours

Tips on the spot

Swim only in the lifeguarded area, during the official dates and hours: in 2026, from 27 June to 31 August, 1.30 pm to 7 pm. Outside these, swimming is forbidden, even on a summer morning. Also respect temporary closures due to cyanobacteria.
Personal craft are forbidden all year: no paddleboard, canoe or kayak of your own. You can rent on site from Aventur’O Lac.
Dogs are welcome on a lead on the estate, but not on the beach or in the swimming area. A dog can go on a pedal boat if you tell the ticket office.
Avoid Sunday afternoons in summer: the car parks can be full from 12.30 pm. Weekdays, Saturday mornings or after 6 pm are much calmer.
There are no bins around the lake: bring a bag to take your litter home. Recycling points at car park P2.

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Barbecues and fires are forbidden, even for a picnic: Iffendic is classed as sensitive to forest fire risk, and restrictions can apply in dry weather.
With young children, there is no need to do the full 5 km: Excalibur, the playground, the Lutins course (from age 3), the beach and a pedal boat ride are enough to fill the day.
Prices shown in 2026 at Aventur’O Lac: tree-top adventure from €9 (Lutins) to €18 (Graal), giant zip lines €9, kayak €9 an hour, canoe €13 an hour, pedal boat €7 to €19, mini golf €3 to €5.
Fishing requires a permit, sold at the lake’s tourist office. A red swamp crayfish that is caught must never be released elsewhere.
For Excalibur, come at sunrise: the sun rises in line with the lake and the site is almost empty.
In a manual wheelchair, call the tourist office (02 99 09 06 50) after heavy rain: mud or forestry work can make some sections difficult.
In autumn and winter, check the hunting days before hiking in the woods.
Drones: the site is very busy and partly protected. Check the regulations and permissions before any flight.

Frequently asked questions

How big is the lake?

About 50 hectares of water (sources give 44 to 50 hectares), in the heart of an estate of more than 220 hectares of forest and heathland.

How long does the lake loop take?

About 5 km, walked in 1 hour to 1 h 30. The path is easy, shaded and almost always follows the water.

Can you swim?

Yes, but only in the lifeguarded area, on the official dates and hours: in 2026, from 27 June to 31 August, 1.30 pm to 7 pm. Outside these, swimming is forbidden, including on summer mornings or in September.

Can I bring my own paddleboard or kayak?

No. Personal craft are forbidden all year. You can rent pedal boats, canoes and kayaks on site from Aventur’O Lac, from April to September.

What activities are there for children?

Tree-top adventure from age 3 (Lutins course), then from 6, 9 and 11, giant zip lines from age 11, pedal boats, mini golf, small electric cars, a playground and the beach in summer. With little ones, part of the lake loop is enough.

How much do the activities cost?

Prices shown in 2026: tree-top adventure from €9 to €18 depending on the course, giant zip lines €9, kayak €9 an hour, canoe €13 an hour, pedal boat €7 to €19 depending on size and duration, mini golf €3 to €5.

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Photograph: OT Pays de Montfort · CC BY-SA 4.0 · Wikimedia Commons