5 Answers

http://en.wikipedia.org/wiki/Viking

... A place to start. 

Vikings required water travel to get their business done.  Living by the water was convenient.

Stacey .....  The fishing for food that you mention above is maybe one reason.  It was easier to travel by water than over land because of all the trees and vegitation.  

Vikings
To the many people who were conquered by the Vikings they were know as pagans, ... Vikings lived up to their adventurous nature by seeking their fortunes abroad. ... Although Kings came from ancient royal families, wealth and blood did not .... 

there are quite alot of reasons for living near the sea 1 quick get away if needed 2 food 3 good look outs 4 they cold travel around the island that they raided on

It was the best place to launch their ships for Europe to rape, steal, burn, murder and wreck havoc along the river ways.