[4] The bay's shores are generally heavily wooded and consist mainly of bold and rocky shorelines interspersed with numerous barrachois (barrier) points and beaches.

[7] The earlier name "St. Andrews Channel", is now used to identify the adjacent arm of the lake to the north falling between the Boisdale Hills and Boulardarie Island.

The long fetch offered by West Bay to the south-west can result in sizeable waves and swells to develop during southwest or northeast gales.

Rifting and regional tectonic plate movements some 360 million years ago formed this directional series of small fault bounded basins between highlands of resistant crystalline rock.

The northern shoreline suggests that the bay is largely underlain by Carboniferous Windsor Group sedimentary rocks, principally shale, sandstone and gypsum.

The southern shoreline is generally the elongated block of Precambrian rocks known as the East Bay Hills, composed of volcanic deposits of the Fourchu Group (ash and lava interleaved with marine sediments) and earlier Paleozoic era intrusive granite and quartzite.

The main excavation of the deep channel (81–82 metres (266–269 ft)) in East Bay appears to be a consequence of glacial erosion, probably over hundreds of thousands of years through the Quaternary.

The cliffs bordering the lake are unusual because they preserve organic sediments predating the last glaciation that provide a window on earlier environmental conditions.

[3] The morphology of the lake floor is influenced by the deposition of glacial till and pre-glacial silty muds that occurred during the last retreat of ice.

The relatively high sea level inferred at this time reflects the continuing depression of the land from loading by glacial ice.

[3][9][10] Sediment distribution in the Bras d'Or Lake is similar to that found in many of the larger coastal inlets on the southern shore of Nova Scotia.

[11] A varied fish fauna includes blueback herring, blackspotted stickleback, American eel and a southern population of Greenland cod.

[14] A marina for local and visiting boaters was completed and opened in the spring of 2013 at the community of Ben Eoin as part of the existing ski hill and golf course complex.