The largest reservoir of fresh water is glaciers. Glaciers are massive bodies of ice that accumulate over a long period of time in high-altitude areas. They are formed from the accumulation and compression of snow. Glaciers store a significant amount of water in the form of ice. When the ice melts, it releases fresh water into rivers and streams, which eventually flows into larger bodies of water like lakes and oceans. Groundwater, ponds, and lakes also hold substantial amounts of fresh water, but they are not as extensive as glaciers. Groundwater is water that is stored underground in porous rocks and soil. Ponds are small bodies of water, often created by natural or artificial means, while lakes are larger bodies of water that form in basins or depressions on land.