An island Gibraltar would dominate the Mediterranean entrance

How would World War II change if Gibraltar were an island in the middle of the strait?

It would become even harder to attack and perhaps the Mediterranean's most important strategic position, provided Britain secured a reliable fresh-water supply.

An island position would allow defenses to cover every approach while denying attackers access from the landward side. Water would be the critical vulnerability, so Britain would need to prioritize desalination and storage to sustain the fortress through a siege.