The fjord-like lakes of this rugged region lie
at elevations from 400 m to 520 m above sea level with the surrounding
mountains rising to over 2750 m above sea level. The area can offer
magnificent freshwater diving, particularly in the winter months
when Kootenay Lake remains unfrozen and the low flows produce visibilities
of 20 m on rare days. Average visibility in winter is more than
10 m, but these dives require drysuits in bone-chilling water temperatures
of +2 C. In late April snowmelt increases runoff into the lakes
and visibility drops to 3 m or less, depending on location.
The Arrow Lakes provide an added complication,
as they are now reservoirs, with mid-summer depths some 20 m above
historical levels. The lowest water levels are encountered in early
spring, at which time it is possible to dive most sites before water
depths increase later in the year. Some sites, such as the Northeast
Arm of the Upper Arrow Lake, have a 3-week dive window in late March
