In our game-party the situation was the next:

Dracula's movement: he is travelling on the sea (with no action, of course).

Lord Godalming: after his movement, in his action gets an event card with a bat on its back -> gives it to Dracula.

The card was the "evasion" (immeditaly playable)

Can Dracula uses this card at the moment on the sea? If yes: where can Dracula travels with it? Anywhere he wants, or only to either of ports maybe?

Thanks for the answers in advance!

The card text i quite clear, just follow it. And there is no reason why Dracula player would not be allowed to use this card when ON the sea.