We leave La Paz and take the bus to the west, along the south side of Lake Titicaca. Titicaca means "grey puma" in Quechua, because it apparently had the shape of a puma (it keeps loosing water, so it doesn't look so puma-like anymore). It is the highest-altitude lake of its kind. While it's water quality keeps to deteriorate (La Paz lies higher, so you can guess why), it is still OK and full of fishes, especially trout and kingfish.
Copacabana is a pretty tourist town at the lakeside and we enjoy a wonderful fresh grilled trout filet here. We also take a 2-hour boat ride to isla del sol (island of the sun), the largest isle in Titicaca, where we have a nice hike. After the busy and polluted city of La Paz, Copacabana (and Titicaca in general) is a nice relief.