The Grey Seal
The grey seal (Halichoerus grypus) is the largest of the three Baltic seal species: adult males may reach over three metres in length and 300 kg in weight. 
There is a great variety in coat coloration and shading of grey seals. Males tend to have a dark brown-grey coat, sometimes nearly black, with a few light patches, while females are generally light grey-tan coloured, lighter on the front, with dark spots and patches.
Project's main site - www.balticseaportal.net
The Ringed Seal
The Baltic ringed seal (Phoca hispida botnica) is the smallest seal in the world - its body length is 130-150 cm and weight 50-60 kg. The weight is varying depending on season, in autumn it can be up to 100 kg.
Characteristic for the ringed seal is the pattern of its fur: light ring-shaped blots on the back and dark ring-shaped blots on the belly.
The Harbour Porpoise
The harbour porpoise (Phocoena phocoena) is the only whale species breeding in the Baltic Sea. The name derives from French pourpois, originally from Medieval Latin porcopiscus ("porcus" - pig + "piscus" - fish).
Harbour porpoise is one of the smallest toothed whales having a stocky body and a rounded snout with no prominent beak.