Unrehearsed valve shutdown training led to confusion underwater
While taking a sidemount technical diving course, I was performing tank shut down drills at around 60 feet (18 meters) and switching to my "usable" tank and regulator. I had not practiced this drill before and simply discussed it with my instructor and another student in the class. While performing the drill, I got a bit confused. I did not have a regulator in my mouth and was exhaling while attempting to switch tanks. I tried to place my regulator from my short hose in my mouth and could not get it as the necklace it was on was twisted. I could not exhale or hold my breath any longer at this point and started to inhale water. My instructor gave me his regulator on his long hose, grabbed ahold of me and we started our ascent. It was a controlled ascent and we performed a safety stop at 15 feet (5 meters). While ascending, I was coughing continuously in my regulator and trying to get a good breath. When I reached the surface, I spit up and coughed up water and secretions. I was assisted back onto the boat and was able to catch my breath.
During dive training it is always preferable to rehearse a new skill on land before the dive. This diver is to be commended for not panicking during the ascent.