Shoreline - the boundary between land and water around a body of water (sea, lake, reservoir).

Defined as the actual length of the lake on the zero isobath.

On the shoreline of land bodies of water, at the junction of different environments (land, air and water) of the formed ecosystems there is the greatest effect of densification of life.

Shoreline is defined differently for different types of water bodies:

for seas - by the constant water level (if any) and by the line of the maximum tide (in case of periodic changes in the water level);

for rivers, streams, canals, lakes, flooded pits - by mean annual water level, except for periods when they are covered with ice;

for ponds and reservoirs - at the normal retaining water level;

for swamps - by the boundary of the peat deposit.

A shoreline cannot have a well-defined length. When measured, the coastline behaves like a fractal, i.e. its length depends on the scale at which the measurement is made. The larger the scale (and therefore the more accurate the measurement), the longer the coastline. It makes sense to measure at a larger scale if the country has a very indented coastline.

Countries with the longest coastlines:

Canada: 202,080 km

Norway: 58,133 km

Indonesia: 54,720 km

Greenland: 44,087 km

Russia: 37,653 km

The shoreline paradox is a controversial observation in the geographical sciences related to the inability to accurately determine the length of a coastline because of its fractal-like properties. The first documented description of this phenomenon was made by Lewis Richardson; it was later extended by Benoit Mandelbrot. The length of the shoreline depends on how it is measured. Since curves of any size, from hundreds of kilometers to fractions of a millimeter or less, can be distinguished for a section of land, it is impossible to pick obviously the size of the smallest element to be taken for measurement. Consequently, it is also impossible to unambiguously determine the perimeter of a given section. There are various mathematical approximations in solving this problem.