Inland ground waterways on which, due to their hydrological conditions as well as existing water equipment, transport of persons and goods using inland waterway vessels is possible. Inland waterways consist of: navigable rivers, navigable lakes, unnatural waterways (canals, lakes, and regulated sections of rivers).

Navigable river - a natural waterway that has been deemed as navigable.

Navigable lake - a natural water reservoir that does not have a direct water connection with the sea and has been deemed as navigable. Navigable canal - w waterway built above all for navigation purposes. It is a hydro-technical construction that has been created outside of a river run. Water from surrounding natural water sources is connected to a canal, therefore a canal is always connected to a river from at least one side.

Regulated river - has a fixed or almost fixed depth that has been achieved through the construction of water steps (dams), with an even, profiled bottom, liquidation of bends, riverbed limited by perpendicular dams. Dams are also equipped with ancillary equipment (locks, slipways) allowing for further sailing as well as the migration of fish. Inland waterways are divided into classes.

These classes define:

1) the maximum parameters of vessels that can sail on such waterways,

2) the minimum height under bridges, pipelines and other equipment crossing the waterway.

Transit depth - the minimum depth of the navigable waterway on a given section.

• Act of 20 July 2017, New Water Law
  Place of publication: (Dz. U. z 2024 r. poz. 1087, z późn. zm.)