© Alamy-Water Frame The Heaviest of all Eels The conger eel, also known as the European conger, is distributed throughout the eastern Atlantic Ocean and is particularly present in the Mediterranean Sea. These robust eels are the heaviest marine eel species within the Congridae family and a favorite sighting amongst European divers, growing up to 3m (9.8 ft) in length and 72 kg (159 lb) in weight! Divers have the greatest chance of diving with conger eels amongst the rocky reefs of the Mediterranean. Congers prefer to hide during the day in the holes and cracks of the reef. Keep your eyes peeled as they are well camouflaged due to their greyish-black coloration. These nocturnal hunters come out at night to hunt smaller fish, crustaceans, squid, and octopuses. To find where you can dive with conger eels, explore the dive site map below.