Mrzeżyno is a summer resort located at the mouth of the Rega, inhabited by 1,600 permanent residents, with approx. 6,800 beds in over 40 various types of recreation centers. Its modern name was established after the war. On earlier maps you can find the name Ost Deep or Treptower Deep.
Before Mrzeżyno was founded in the mid-15th century, Trzebiatów used the port of Regoujście, located slightly east of today's port. In 1456, Regoujście was covered with sand due to storms and unfavorable winds / another version of the port's decline talks about the inglorious role of the inhabitants of Kołobrzeg who, by sinking ships with stones, blocked and destroyed the competitor. However, soon the inhabitants of Trzebiatów dug a new 1.5 km long bed for Rega. The excavation was, for those times, a great technical achievement. Since then, new residents began to arrive in the new settlement.
In 1538, Mrzeżyno was inhabited by 19 families, and in 1587 by 24 families. According to the records of the Trzebiatów town hall, in the 16th century, merchants sailed from here to Lübeck, Stralsund, Gdańsk, Bornholm, Copenhagen and Bergen, because from 1365 Trzebiatów was part of the Hanseatic League. Not only Trzebiatów, but also Gryfice's trade was carried out by sea through the port in Mrzeżyno.