When walking in the desert, and particularly if you're poking about in sandy, rarely visited tombs, you should keep an eye open for snakes. Although extremely rare and shy, there are a number of species of venomous snakes in Egypt, and you don't want to test the local supply of antivenin.
South of Aswan -- Until the 1970s, there was a whole country between Aswan and Sudan. With the completion of the High Dam in 1971, however, and the subsequent flooding of the river valley, Nubia was inundated and submerged beneath more than 5,000 sq. km. (almost 2,000 sq. miles) of water that was named Lake Nasser. (Actually, only the Egyptian portion of the lake is named Lake Nasser. The Sudanese, with a fine sense of irony, named the portion that spilled southward over the border Lake Nubia.) Now there are just three major sites south of Aswan, one of which is the dam itself. The other two -- the Temple of Ramses II and the temples of Philae -- were rescued from the rising waters by the international community and transplanted to safe locations above the high-water mark.
Sound & Light Show at Philae -- The show at Philae is perhaps a little more muted than its Karnak counterpart, but it follows the same formula: music, lights, and a voice-over that runs you through the history of the temples. Even if you're not a particular fan of sound-and-light shows, this one's worth it for the experience of being out on the river at night and seeing the temples lit up. There are three shows a night, and both the times and the languages vary, so it's wise to check with a travel agency in town or with the tourist information office rather than relying on the accuracy of the following times. Admission LE55 ($10/£5.10). Winter shows 6:30, 7:45, and 9pm; summer shows 8, 9:15, and 10:30pm.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.