Edi was a marine biologist working off the coast of california. She wore a special diving suit to see animals in the deep ocean up close and personal, without being crushed by all the pressure down there. During this descent, edi had her lights on, but when she got down to around 800 feet, where the water gets really dark, she turned them off. It's a phenomenon called bio luminescence. Animals will use e huge amounts of energy to give off light. But watching this light show, it really struck edi that she didn't understand why they were doing this.