Science and sightseeing come together to bring sustainable tourism to the Red Sea: As tourists continue to flock to the coral reefs of El Gouna, marine biologist Angela Ziltener is helping to guide their experience to ensure it is both enjoyable and sustainable, this CNN video shows (watch, runtime: 02:30). Ziltener’s primary aim is to protect the many Indo-Pacific bottlenose dolphins found in the area. She has spent years observing and researching them, with much of her work focused on their sleeping patterns. Ziltener has discovered that the sensitive creatures hunt in the ocean at night and come back to the coral reefs during the day to sleep — with one side of their brain actually staying awake. Making sure that tourists know how they can visit the coral reefs without disturbing the dolphins in their natural habitat is a crucial part of preserving the region’s diversity of marine life, she says.