Remote even by Kyrgyzstan standards, magnificent Köl-Suu lake stretches over 10km through a sheer mountain gorge that reaches nearly to the Chinese border. It's hard to grasp the true scale until locally run boat trips (from $200 per person) strike out for the centre of the lake, where they seemed dwarfed by rock walls on every side. At 3500m the weather here can change rapidly so be sure to pack warm and carry extra provisions.
It's over 150km from Naryn through increasingly bad roads and two border checkpoints, but the final 7km from Jyrgal jailoo into the Kurumduk Valley's dramatic panorama of craggy peaks would be worth the trip even without the lake to cap it off. Horses are available to hire for the river crossing beyond Jyrgal or for the full trip up to the lake, but a determined driver in a reliable 4WD can sometimes make it all the way to the lake's shore.