I puttered right on past the first boss and I no longer see any radar indicator for its location. At the start there is the red indicator on the edge of the radar but when I went past it, it went off the radar and I can no longer find it. There's not much for land marks so I have no idea which direction I'm going or if I've turned 90 degrees or 180 degrees. Just lost at sea now...
Also, on Linux the animation for the explosive harpoon doesn't seem to work so I have no idea if I'm throwing a regular or explosive. Low quality settings make the game unplayably dim and medium settings have artifacts all over the bottom half of the screen.
Edit: The explosive harpoon, I guess, is not available during the first boss? I thought there was a problem with the animation but it works fine on boss 2-4.