Let's come up with an amphibian race!

So, amphibians, like other races, have a penalty when transitioning between land and sea. To travel by land, they need to buy a ship, and then they can travel across water without penalties. Amphibians have a penalty when traveling on land. Therefore, it will take a considerable amount of time for them to travel through dungeons and across land to reach the water (underground seas are not connected to surface seas). But land-based creatures will quickly recoup the cost of their ship. However, amphibians travel faster across water.

Added 1 minute later
Let's call them Garians. It's more interesting and sounds better.