Here are some pictures taken from my summer on the ice. These illustrate to an extent what we mean by sea ice and multi-year ice.
Pack ice breaking up in June, 1985, Eureka Sound.
The blur at upper right is the Twin Otter propelor.
Thawing ice, Eureka Sound. There is a drainage hole in the middle foreground.
Most of the blue is freshwater sitting on top of ice. Most of the area in this photo
would be ice-free at some point in the summer (note icebergs in background).
Multi-year ice connected to Ice Island, May 1985.