Lago Electrico lies about 10km north of Mount Fitz Roy, as the crow flies. It is filled by the meltwater of the Marconi Glacier on the eastern edge of the South Patagonian Ice Cap.
To get there you normally start out from the bridge on the Rio Electrico (around 20 mins drive north of El Chalten) and hike through woodland along the banks of the river to Piedra del Fraile. The hike from Piedra del Fraile to La Playita is more challenging but has a clearly marked path.
From the Electrico lake and river there are a couple of side-hikes worth exploring: the Pollone Valley and Piedra Negra. Both of these are best tackled with a guide.
Photos of Lago Electrico
Map of Lago Electrico