Or that sound travels across water? I assume it’s because usually there are blockages, tree/buildings horizontally, while in high-rises and boats there are nothing blocking sounds
Edit. The myth here is that sound travels across water and upwards more than any other direction. Apologies if it was not worded well
If the air over the water is cool, and it often is, sound travels better through the dense cool air. And you’re right that there’s no obstacles or terrain, too.