Being a closed interior sea, the Pontus has no noticeable tides. Marked changes of level are caused by the action of the wind. In the liman of the Boh, for example, they produce 20 centimeters difference of level in a day, sometimes even 40 centimeters; in the bay of Yah6rlik as much as 46 centimeters. The Sea of Azof becomes 45 to 90 centimeters deeper when there is a west wind, up to 1 meter deeper in the case of south winds, and shallower by an equal amount when the winds are in the opposite direction. Slight changes of level are dependent also on the seasons. The Black Sea has its lowest water level in February, when the region which it drains is covered with snow; the highest in May and June, as a result of the melting of the snows and the early summer rains. These fluctuations, however, amount to only 25 cm. The currents of the Black Sea, too, are inconsiderable, because of its isolation. Outside of local currents which are caused by winds, we know of only one greater current, weak in itself, which encircles the Pontian Basin in a counter clock-wise direction and may be traced to the cyclonal motion of the air. The same conditions obtain on a smaller scale on the Sea of Azof and are reflected in the direction of the tongues of land along the coasts.
Despite the fact that the deep-sea region of the Black Sea is poisoned with sulphide of hydrogen, it possesses a rich flora and fauna in its surface layers. Enormous shoals of all kinds of fish — sturgeon, hausen, sterlet, "kephal," "bichok," "balmut," come to the coast and into the limans of the river deltas. For this reason the Pontian fishing industry has been considerable for thousands of years. The extraction of salt from the limans and salt lakes is also important. Before the age of the railroad the abundance of fish and salt of the Black Sea created a special trucking trade in the Ukraine, the so-called Chumaki, who came to the Pontian strand in whole caravans of oxcarts to take dried fish and salt in exchange for grain.
The Ukrainian coast of the Black Sea begins at the delta of the Danube and ends at the western spurs of the Caucasus. The greater part is flat coast, the smaller, steep coast.
At the northern Kilian arm of the Danube delta, where now the descendants of the Zaporog Cossacks gain a scanty living thru fishing, begins the coast of the Ukraine. The steppe approaches the sea with a steep declivity, which is bordered by a narrow strand of sand and pebbles. The coast runs evenly as far as the Dnieper delta, without any indentations. Even the famous port of Odessa is an artificial harbor.
Only at a point where a river, a streamlet, even a balka (step-glen, ravine) opens into the sea, is the steep incline of the steppe-plateau broken. We then see before us an enormous pond as it were, at the upper end of which the water-course enters and the lower end of which is locked from the sea side by a land-tongue or bar (Kossa, Peresip) as by a flat dam. This sea-water lake is called liman in Ukrainian.
Wherever a stream of great volume empties into a liman, the bar is severed at one or more places. These liman deltas are called, in Ukrainian, hirl6. Limans which have such connections with the sea are broken. Of such a kind are the limans of the Kunduk, Dniester, Boh and
Dnieper. Where a little streamlet discharges which has not a sufficient volume of water to cover the loss from evaporation of the liman surface and still retain an excess for keeping open the outlet, then the bar of the liman is without an opening and the water contains a great deal of salt. Of this kind are, above all, the limans of Kuyalnik and Khadshib6 near Odessa, the large, deep Tilihul and many smaller ones. The water and the mud of such limans possess healing powers, and every summer thousands of patients travel to the hot shores of the limans to regain their health.
The limans are simply submerged eroded valleys of steppe rivers which are now being filled in by alluvial deposits. Therefore, the limans of all larger rivers are too shallow to serve as good harbors for the larger sea-going vessels. The liman of the Dniester allows entrance only to small ships drawing two meters of water; the gigantic Dnieper liman is only 6 m. deep, and only the Boh liman is accessible to larger sea-going ships. Systematic dredging, however, could, without a doubt, bring relief, and would change a number of the limans into profitable harbors.