Something we noticed in the student groups interacting with the virtual ship is that they chose to deploy very shallow Argo floats with a maximum depth of 300 m (group D and F). These floats gave quite a lot of NaN/0 results when they "collided" with the coast. This might be realistic, as the currents that follow the coastlines are usually deeper, but is something that requires attention in the virtual ship.
Also, in these cases gliders might be a more suitable choice of equipment than Argo floats.