Totally unbelievable! Good SciFi is at least plausible by known science. This movie is so fake I couldn't watch the end. Decompression is not needed at the depths they were diving in. Why didn't they use the device to attract the sharks away from the Olympic activities. I guess they never heard if shark nets. They're fighting sharks in what is essentially a large aquarium. The list of stupidity goes on and on. If you know NOTHING about sharks I guess you could believe it but, fir anyone that dives, grew up on the water or knows anything about sharks it's too much to swallow.