It is an intricately shaped loch opening onto the Firth of Lorn near the easternmost point of Mull.
Its waters are shallow and the loch dries almost completely at low tide.
A minor road runs south from Lochdon and around to Grass Point at the point where the loch meets the open waters of the firth.
[1] There are both a terminal moraine and deltaic sand deposits around the northern end of the loch, a product of meltwater flow at the end of the last ice age.
[2] The shores of the outer part of the loch are formed from basalt lava flows of Palaeogene age whilst the inner parts of the loch extend across Palaeozoic basalt and also Mesozoic sedimentary rocks including Triassic sandstones and Jurassic Lias strata.