Any form of water concentration on the land surface - rivers, lakes, swamps, reservoirs, glaciers, or any form of moisture concentration (for example, snow cover).

Water bodies are seas, oceans, rivers, lakes, swamps, reservoirs, groundwater, canals, ponds and other places where water is permanently concentrated on the land surface (e.g. in the form of snow cover). Water bodies form the basis of water resources. Many sciences deal with the study of water bodies. Hydrological methods of measurement and analysis are used to study water bodies and their regime. From an ecological point of view, water bodies are ecological systems.

Water bodies, depending on the features of their regime, physical-geographical, morphometric and other features, are divided into:

surface water bodies;

underground water bodies.

Surface water bodies include:

seas or their separate parts (straits, bays, including bays, estuaries and others);

watercourses (rivers, streams, channels);

reservoirs (lakes, ponds, flooded quarries, reservoirs);

swamps;

natural underground water outlets (springs, geysers);

glaciers, snowfields.

Surface water bodies consist of surface waters and the lands covered by them within the coastline.