The Maullin River is the only drainage of Lake Llanquihue, the main watershed for the Chilean Andes in the region. It generally flows southwest approximately 50 miles from the outlet to the Pacific Ocean. Resident fish include Rainbow and Brown trout and Atlantic salmon.

The Maullin consist of three distinct sections all requiring drift boat fishing. The banks are brush and tree lined making bank fishing difficult. Some sea-run Browns may be found in the lower section of the river. In the upper and middle sections of the Maullin river the rainbows, resident browns and atlantics. Occasional sea run fish can be found in the lower section. Fishing si done from drift boats, 1 guide per two fishermen.