The cursor icon for the pick, shovels, and hammers all need to be slightly outlined or darker so you can see them better.
Everything in game that is used as a tool or has a unique mechanic, needs some basic tool tip when highlighted. (there could be an option to turn these off)
Perhaps in later production stages you could add in more of a wake animation when the ships cut through the water? A trails through the water of bubbles or churned up water and some sort of waves coming off the bow of the ship as it moves through the water for more immersion. (no pun intended)