The presence of floating ice in northern regions bears significant economic, environmental, and social implications. Navigation is one of the areas where the influence of floating ice is particularly evident. The history of ice threats to navigation and hardships experienced by early mariners are well known. At present, even with all the new technologies, ice can pose serious challenges. A major threat arises when ice around a ship starts to converge. The compression or ice pressure builds up if wind and water currents drive the ice cover against a land boundary. The ice cover compresses and ice accumulates to form ridges. If a ship is caught in such a situation, pressures on the hull will be high. Additionally, the ridges can introduce serious impediments to ship progress. Consequently, ice resistance would dramatically increase, and the ship can become beset. In extreme cases, ships can be damaged, and smaller vessels can be completely lifted onto the ice. To understand how ice interacts with ships, we must start with ice properties and characteristics of ice covers. Ice ridges, for example, may represent formidable obstacles to ships. The way those ridges form and their properties determine the level of resistance that ships may encounter. Although the effects of ice pressure are important over all Arctic and northern waters, the focus of this discussion is on the Canadian experience. The particular conditions that lead to ice pressure build-up and the impact on shipping at various specific locations in Canada are surveyed. The discussions conclude with a description of a Captain's experience in dealing with ice pressure on the Great Lakes.