The canals in Amsterdam are frozen which is rather unique because the winters are almost never cold enough. But this winter you can skate and walk on the ice.
To put the skates on people use the little boats to sit on.
I didn't go on the ice, it is to slippery for me and a bit difficult to get on and of here by climbing over the boats. Skating I used to to when I was younger, but I am to scared now to fall and break a leg or shoulder, which happened to a friend of mine of the same age.