Grey seals are the larger of the two seal species in Irish waters. Males are known as bulls and females are known as cows. Males grow to approx 2.5 meters in length, weighing 300kg, while females grow to approx 2 meters and can weigh up to 180kg. The body of the grey seal is torpedo-shaped and is covered all over with a coat of short fur.  The colour of seals varies considerably; males have fewer spots on their undersides while females are lighter in colour on their back and underside area but with dark areas on the underbelly.
 
Grey seals have four flipper-like limbs, each containing five webbed digits. Their manoeuvrability on land is awkward, but they are very agile swimmers in the sea.  With large forward-facing eyes, grey seals have excellent vision both on land and when submerged. Grey seal haul-out sites are established in areas of rocky coasts or on steep sandbanks. Every year during the mating and pupping season, the seals will gather in large colonies of several hundreds, on their rookeries or breeding sites along the coastline which are often on uninhabited islands.
 
Outside of the mating and pupping season,  they spend most of their time at sea in between periods spent hauled out at resting sites. While at sea the grey seal spends up to 80% of its time underwater hunting with the remaining 20% of the time spent breathing at the surface.