The historic fortress of Saladin known as Pharoah's Island is located just off the shore of Taba, Egypt. It is known as Gezirat Pharaon in Arabic. The island can be seen from the 3 cities of Taba, Eilat, and Aqaba and features an impressive military structure with fortified walls.
The island itself is quite small and can easily be toured as part of a day trip. There are snorkelling trips out of Eilat that will take you to the reef for snorkeling, out to Pharoah's Island for lunch and a tour. Be aware, however, that the influx of tourism has largely destroyed the reefs immediately surrounding the island. You will see fish life, but very little live coral. At the current time, there is no separate Egyptian visa needed for these tours.
Alternately, you can take a ferry from the Egyptian coastline out to the island. I do not recommend this at the current time. As few tourists go this route, the boat only runs on demand and the captain was asking $20 a head when we were there. Given that the daily snorkel tours run only a few dollars more and the distance could almost be swum, this is a very big rip-off. The fortress itself has been nicely restored by the Egyptian Antiquities Organization and in current times is not swamped with tourists. On a slow day in the off season, you may even get the place to yourself. Take the time to walk around the walls and envision yourself following in the footsteps of Lawrence of Arabia, who passed the same way almost a century ago.