Research on Wrangel Island (Belikov 1976) and Hudson Bay (Kolenosky and Prevett 1983) suggested that polar bears select den sites based on specific topography and habitat. Whether the habitats are scattered or concentrated, however, all denning areas have microor macrohabitats that predictably catch snow in the autumn and early winter (Durner et al. 2003). In the mountains, snow-catching features are obvious. The snow-catching ability of the very flat terrain in coastal Alaska, where until recently denning was presumed to be insignificant, is not so obvious. There, the most frequently used denning habitats are along coastal and river banks. Although the mean bank height where female bears den is 5.4 m (SD = 7.4 m), banks as low as 1.3 m provided sufficient snow depth for successful denning (Durner et al. 2001). The Alaskan northern coast gets relatively little snow. However, the landscape is so flat that what snow there is, is blown incessantly across the plain throughout the winter. Any areas of relief in the otherwise flat terrain are filled solidly with snow from the very early winter. Banks used for denning in Alaska most commonly had water or level ground below the slope and relatively level ground above, enhancing the chance for sufficient snow build-up for denning (Durner et al. 2001).

Across the range of polar bears, most denning, whether in concentration areas or dispersed, occurs relatively near the coast. In early visual surveys, Harington (1968) found that 61% of dens located over broad regions of the Canadian Arctic were within 8 km and 81% were within 16 km of the coast. All dens seen by Stirling and Andriashek (1992) in the Canadian Beaufort Sea were along the coast. Likewise, Stishov (1991) reported that 83% of dens found during surveys of northern Russia were in snow banks formed under shore slopes and precipices. Most polar bear dens were within 3 km of the coast of Svalbard (Larsen 1985). Even on Wrangel Island, where bears move inland to den in high mountains, most are located within 8 km of the coast. The main exception to coastal denning appears to be the Hudson Bay area, where females moved from 29 to 118 km inland to traditional denning areas (Kolenosky and Prevett 1983; Stirling and Ramsay 1986).

The trend toward denning very near the coast has now been confirmed in most regions by radiotelemetry studies. Telemetry allows investigators to locate dens anywhere bears establish them. More than 80% of maternal dens found on land by radiotelemetry in the Alaskan Beaufort Sea were within 10 km of the coast and over 60% are right on the coast or on coastal barrier islands (S. C. Amstrup, unpublished data). Messier et al. (1994) used satellite telemetry to learn that maternal dens in the Canadian High Arctic were widely scattered in coastal areas, and averaged 8.6 km from the coast. Ferguson et al. (2000a) reported that most dens found using telemetry in the Canadian High Arctic and Baffin Bay areas were within 20 km of the coast.