Fleeing Flea

There is a flea being chased by a snake and it needs to get safety as fast as possible. The flea is sitting on one of the corners of a right parrallelpiped with side lengths of $2$, $2$, and $3$ and can run at a pace of $2.5$ units per second. It is trying to reach the safety of the direct opposite corner, how many seconds until it can reach the other corner?