Tossau de Mar (2750m) via era Restanca, Estanh de Mar, Estanh de Rius loop

Pont de Rius- Refugi and Estanh dera Restanca - Estanh de Mar to the Serrada de Mar pass - out and back scramble up Tossau de Mar (2750m) - descend past Estanh dera Colhada, the Estanh Tòrt de Rius and the Basses de Tòrt until the Estanh de Rius, from there the loop is completed by descending through the Barranc de Rius passing through the Pleta de Calders, the Basses de Rius and the Plan de Rius.

The loop follows well-marked paths and trails and can be classified as moderate though physically demanding hiking. Adding on the optional section to Tossau de Mar makes it an alpine climbing route as this out and back requires route finding in alpine terrain and the last section follows a sharp ridge involving hands-on maneuvering (IIº) with significant exposure.

I did this before the road was closed to private vehicles (july 10 onwards you need to take the shuttle bus from Arties) so parked and started at Barraca de Rius (more like a shelter than a hut and is closed). Follow sign left upwards to the "Refugi dera Restanca" along a clear path that brings you to the dam of the Estanh dera Restanca. Cross here toward and past Refugio dera Restanca and continue along the lake until just before the end waterfall where the path turns left uphill. This climbs up until the signposted crossroads of the Plan de Mar, take the right path here towards the "Estanh de Mar" (yellow signs), through the meadow then climbing up to reach the N end of the Estanh de Mar. Follow clear path and rock cairns along left/SW side of the lake until reaching the clearing at the end (S) of the Estanh de Mar, where there is a signposted intersection. Turn right towards the "Estanh de Rius", across the stream and continuing around the Estanh de Mar.

After going around the lake, the path climbs steeply in switchbacks while giving magnificent views over the Estanh de Mar. At the Coll de la Serrada de Mar, the view opens to the other side towards the Estanh dera Colhada and the Estanh Tòrt de Rius.

From this pass there is the option to do the out and back trip to the summit of Tossau de Mar, which starts following a trail (N, rock cairn landmarks) that follows the wide ridge with a tendency to rise but with some short descents until ascending a steep grass and stone slope to the summit ridge. The ridge is horizontal but sharp with exposure on both sides. Though not technical it does require some scrambling and about 10 meters from the summit landmark you have to descend a few meters to the left of the ridge (Slope W) all the way down and then climb up (IIº) through a small channel-chimney with good handholds back to the summit ridge a few more meters to the top of the Tossau de Mar (2750m). It is a narrow and aerial peak crowned by a summit landmark with amazing 360º views. My GPS map does not indicate the actual summit as I accidentally paused just before the last few minutes to the top. However it is impossible to miss.

Follow the same route to return to the Coll de la Serrada de Mar. From here a well-marked path descends towards the Estanh dera Colhada and follows to the right of it taking a NW trend, then around to the N end of Estanh Tòrt de Rius, passing between the set of small Basses de Tort. You come to a signposted intersection next to the Estanh de Rius, here turn right towards "Restanca" and "Pont deth Rèssec" following a clear path and GR signs. This descends with an E trend along the right side of the valley that forms the Barranc de Rius. Continue down the valley until the signposted intersection where you turn off the GR trail and take a path to the left towards "Pont deth Rèssec". This descends into the meadows and crosses the torrent of the Barranc de Rius. Many cows and friendly horses often there. After crossing the Plan de Rius, the path (landmarks) makes a very short climb and immediately begins to descend along the left side of the ravine, switch backing along slopes of wildflowers to finally cross the Barranc de Rius stream over a bridge made of logs to connect to the parking and complete the loop.

NOTE: my garmin watch recorded the distance as 19km and 1400m elevation gain - just for reference for planning as the wikiloc recording is not as accurate.