Loch Arienas is an extensive, lowland, freshwater loch on the Ardtornish Estate on the Morvern peninsula in the Scottish Highlands. It lies in a west-northwest to east-southeast direction, is approximately 3.2 km (2.0 mi) long and 1.21 km (0.75 mi) wide, and is at an altitude of 12 m (39 ft). The northern shore of the loch is mostly regular in shape, while the southern shore is irregular. Its average depth is 17.2 m (56 ft) and its maximum depth is 35 m (115 ft). The loch was surveyed on the 18 and 19 of August 1904 by John Hewitt as part of Sir John Murray's Bathymetrical Survey of Fresh-Water Lochs of Scotland 1897-1909.^[4][1][5]

Loch Arienas
Loch Arienas
Location	Morvern, Lochaber, Scotland
Coordinates	56°35′44″N 5°46′39″W / 56.59569°N 5.77756°W / 56.59569; -5.77756[1]
Type	freshwater
Primary inflows	Arienas Burn, Allt Àgh Choire[2]
Primary outflows	Loch Doire nam Mart, River Aline[2][3]
Basin countries	Scotland
Max. length	3.2 km (2.0 mi)[4]
Max. width	1.21 km (0.75 mi)[4]
Surface area	170 ha (420 acres)[1]
Average depth	17.2 m (56 ft)[4]
Max. depth	35 m (115 ft)[4]
Water volume	29,300,000 m3 (1.03×109 cu ft)[4]
Shore length1	8 km (5.0 mi)[1]
Surface elevation	12 m (39 ft)[1]
1 Shore length is not a well-defined measure.

The loch holds native wild brown trout and permits are required to fish the loch.^[6]

In the wood on the northern shore of the loch are the remains of charcoal burners’ huts and charcoal platforms. There is also a stone dyke dating from approximately 1780, which may have been used to enclose the wood to protect it from grazing animals.^[7]