Increasingly awash in high water, the romantic city of Venice is counting on high-tech floodgates to save it from drowning. Environmentalists worry that the gates may destroy the fragile lagoon that surrounds the city.

The 1988 Yellowstone fire may have been one of the worst in human memory, but nature has had eons of experience with such events. NOVA accompanies scientists who are studying the surprisingly rapid recovery from the blaze. Narrated by Peter Thomas.