I was out in my nooby character boating then suddenly noticed that I was aggroed and heard combat noises. I had no idea what was happening and instinctively boated away thinking it was ants. I was over the water and noticed that I was still getting hit, so I thought it must be mosquitos since I don't see any bats? Suddenly I die and get the death screen. 4 seconds after death, the walruses finally appeared and I took this screenshot. I'm not sure if this is because I was using the amber client and the walruses would not load until after I died, but everyone should be careful of invisible walruses.
