If you play the video at 30 frames/s, taking one picture/second is a 30x speedup. If your boat sails at 3mph, the time lapse at one picture/second will be a simulated 90mph. How much of a road can you see driving a car at that speed?
Taking the problem by the other end, figure out your "cruise" speed when in a car, divide by the boat speed. This is your "acceptable speedup". This speedup is your timelapse image interval multiplied by the framerate of the playback (20-30fps).
Of course if you want to shoot the whole cruise (say 3 hours=10000s) and make that a 10mn video (600 seconds) then you have to take 12000 pictures, roughly one picture/second but it can be a bit fast.
Keep in mind that the fjord cruise is taken from high above water in a wide fjord, so the feel of the speed is much less and you can use greater speedup factors. This would also be true if you drive your car in a desert (vs. in a forest or downtown). But picturesque waterways are rareseldom in a very open landscape.
Last, shooting too fast may induce more wear in the camera, and require more storage(*) and/or battery capacity but you can drop frames to slow down the final video. If you are too slow when taking the pictures, you can't fix it later.
(*) Of course for a time lapse, you may set your camera to a lower resolution or lesser JPEG quality.