Another thing we learned when my very good friend and dive buddy Davo did not surface. It was the last dive of the day. Drift diving in Heavy currents. 5pm on the equator, strong glare. Small group of islands in the middle of a very deep channel, 12-15miles from the main island. Davo made a last drop with just a reel. At the end of the drift, everyone else met the boat, but Dave wasn't there. He couldn't be located on the surface, couldn't be heard. Returning to the beginning of the drift, a group of friends made desperate repeated drifts looking for his body. As it became dark, there was no other option but to return to port and report the incident to the Police.
At the end of his drift, Dave was quite calm. He could see the boat and waived his Urukay at them, the boat was busy picking up the other divers, one of whom he figured had landed a fish. No worries, Dave swam against the current to maintain position as best he could. He had a whistle which he was blowing to alert them to his position. Then the boat moved back to the top of the drift. The currents in these parts of Indonesia are very strong. Dave is the best swimmer I know. He regularly swim trains. He swam at full kick for over an hour fighting the current trying to stay as close to the small island as possible. As it grew dark he had to make a big decision.. He ditched the Urukay, his belt, and kept his knife. He knew he would need to swim the 12-15 miles through the night to the main island. Unsure of the sweep in the Channel, he made his best guess and swam in the trajectory he thought would get him close to the main island of Sumbawa. He kept his knife as he had decided that if the was attacked by a shark, he would cut his arteries. In the glimmer of dawn, Dave saw a local fishing boat, swam to it and was rescued 1/2 mile from shore.
The point of this story is that you should always call for help first, and that you can never assume that your buddy didn't surface.