Glaciers are huge bodies of dense ice. They are formed from snow precipitation. The glaciers compress under the weight of the snow layer. If glaciers are formed on a sloping terrain they slowly descend downhill moving under their own weight. Generally, the glaciers are formed in the regions where snow accumulation exceeds its ablation (ablation is related to all processes that remove snow, ice, or water from a glacier or snowfield) over centuries. During the motion of glaciers, many large cracks (crevasses) appear in the ice and sometimes high columns of ice (seracs) are formed during ice deformation under stresses induced by the glacier weight. During the motion over land, glaciers transport soil and rocks from the land surface and may change the surrounding terrain. Some of the glaciers melt at low heights above the sea, the others reach water in polar regions. Accumulation of glacial ice is considered the largest reserve of freshwater on the planet. The amount of ice is estimated as 69% of the Earth’s freshwater. The modern glaciation on the Spitsbergen archipelago covers a large territory of Spitsbergen. Some of them are tidewater glaciers, the fronts of which terminate in the sea. The largest glaciers of Spitsbergen are in the eastern part of the islands. The dominating type of glaciers in Spitsbergen are large contiguous ice masses divided into many smaller streams of ice. When icebergs melt in the summer, a significant amount of fresh water is formed, which has a significant effect on the temperature, density, and salinity of sea water, its circulation, thermal and strength properties of sea ice, and its distribution and thickness in coastal areas and in fjords where tidewater glaciers end. Meltwater flowing from the surface of these glaciers into the sea during the melting period has the same effect on the state of sea level. A tsunami wave generated by the motion of the Tuna Glacier in Svalbard was studied. The properties of this tsunami wave were similar to a landslide tsunami. The wave amplitude was 30 cm, the period was 93 s, the period of disturbances after the wave was about one hour. Some of the glaciers are polythermal, which means that their bottom part contains some meltwater. We found a flow of meltwater from the Paula Glacier which causes supercooling of outflowing freshwater in the winter sea.