giant's kettle

The Marmit is a small stretch of "giant's kettles" — cylindrical hollows carved into the limestone riverbed of the Ain by centuries of erosion, right beside the bridge that connects Pont-de-Poitte to the neighbouring village of Patornay in the Jura department. It's a compact but striking stop for travellers exploring the region's lesser-known natural sights.

What exactly are they?

Known locally as "marmites de géants" or "marmites du diable" (giant's or devil's pots), these are round, smoothly worn depressions in the rock. They formed as swirling river currents dragged stones, gravel and debris across the riverbed for centuries; that spinning load of rock fragments acted like a natural drill, hollowing out cylindrical, bowl-shaped cavities with rounded rims. Frost action and fluctuating water levels keep reshaping the surface, so the erosion is technically still ongoing today.

Where are they and how do you get there?

The formations sit directly in the bed of the Ain river at Pont-de-Poitte (postcode 39130), best seen from the bridge leading to Patornay. From there, a signposted footpath follows the Route de la Saisse along jagged, fractured limestone outcrops toward the Saut de la Saisse waterfall, which forms a natural continuation of the same eroded landscape.

What will you actually see?

The view is at its best when the river runs low, exposing the full pattern of cylindrical hollows of different sizes — some holding still pools of water, others bone dry. The riverbed looks almost like a natural stone checkerboard, cut through with cracks and kettle-shaped pits carved by moving water. It's worth continuing on to the Saut de la Saisse waterfall nearby, formed on the same stretch of river.

Can you swim or wade in?

It's not advisable. The rocks are unstable and slippery, and water levels can rise suddenly and without warning if there's an issue at the upstream dams that feed Lac de Vouglans, into which the Ain flows a few kilometres downstream. A safer way to experience the river is by kayak or canoe, on organised trips further down toward the lake.

When is the best time to visit?

Aim for a period of low water — typically late summer into early autumn — when the riverbed fully exposes the kettle formations. In spring or after heavy rain, water levels tend to be high and the marmites partly or entirely submerged.

Frequently asked questions

Is there an entrance fee? No, it's a natural rock formation, freely accessible with no tickets or barriers.

How long does a visit take? The viewpoint at the bridge takes just a few minutes, but the walk along the Route de la Saisse to the Saut de la Saisse waterfall usually takes 30–60 minutes round trip.

Is it suitable for children? Yes, as a viewpoint from the bridge — but because the rocks near the water are slippery and unstable, it's best not to let young children climb down into the riverbed itself.

Are there other attractions nearby? Yes — the Saut de la Saisse waterfall is just a few hundred metres further along the same path, and Lac de Vouglans, popular for kayaking and sailing, lies a few kilometres downstream.