The islands are home for approximately 3,500 polar bears. Polar bears (latin: ursus maritimus) are the largest species of bear in the world. Males weigh between 300-700 kg while females weigh 150-350 kg. The length of adult polar bears varies from 180–260 cm. Weight varies dramatically seasonally, especially among females that can more than double their body weight from the spring to the late summer. Polar bears are typically off-white in colour, but vary from grey, through shades of white to yellow. Adult males can be distinguished from females on the basis of their larger size, but more reliably on their more powerful necks that looks wider than their heads. Compared to other bears polar bears have: a long narrow head; a head that is relatively small compared to the body; small, heavily furred ears; claws that are short and strong; canine teeth that are long; and cheek teeth that are sharper. These features have been selected for in polar bears as a consequence of their almost purely carnivorous way of life.
You have to expect polar bears anywhere and at any time in Svalbard outside the permanently inhabited settlements. The probability of meeting a bear increases towards the north and east. But polar bears have even been seen inside the settlements, especially in times of darkness. The highest risk to meet a polar bear on the road will be in the early morning, after hours with little traffic. Because of the polar bear danger it is necessary to carry weapons outside of built-up town area. But - as in Svalbard polar bears are strictly protected by the law - one may shot only in case of direct danger to human life or health.
For more information check the article "Polar bear (ursus maritimus)" on the Spitsbergen-Svalbard website.