Columbia Icefield .

This massive field of ancient ice covers 325 sq km (125 sq mi) and reaches depths estimated at 385 m (1,270 ft). It is composed of the Athabasca, Stutfield and Dome glaciers. Straddling the Continental Divide, the icefield feeds four of the continent’s major river systems: the Columbia, Fraser, Mackenzie and Saskatchewan. Meltwaters from the icefield flow to three different oceans (the Pacific, Arctic and Atlantic). Called a ‘hydrological apex,’ it is one of only two in the world (the other is in Siberia). Markers at the icefield indicate the rate at which the toe of the Athabasca Glacier has receded this century. Tours of the glacier given on custom designed Snocoaches from April 20 to Oct 15, depart every 15 mins daily 9 am - 5 pm. $23.50 adults, $5 six to 15, 762-6700. Ice-walk tours are also available mid-June to mid-Sept, book by calling the Jasper Adventure Centre at 852-5595 or 1-800-565-7547. 125 km (75 mi).