DIVERS: Rubin (PADI deep diver, 300-plus dives) and Ella (AOW, 200-plus dives)

SITE: Deep dive off California coast

CONDITIONS: Sunny and clear, slight chop, 120-plus feet of visibility, water temp 68°F, negligible current

The plan was to take pictures of a kelp forest at 120 feet. Due to the depth, Rubin and Ella agreed to stay outside the forest, shooting along its edge, and then return to the anchor line to ascend. At depth, however, Ella followed a fish she was photographing into the canopy. Rubin followed some distance behind. Trying to fit through dense growth, Ella was snagged by kelp strands. Instinctively, she turned to see what was holding her. Doing so wrapped the kelp around her legs. Trying to push away snagged her computer, and her left arm became entangled as she flailed, trying to free herself. She tried turning the other way, but this made things worse because kelp had snarled on her valve. Rubin caught up with Ella, who was struggling and starting to breathe hard. He signaled for her to stop and spent five minutes disentangling her. The pair retraced their route to clear water; with Ella’s air low, they ascended where they were, made a safety stop, surfaced and swam back to the boat.

WHAT THEY DID WRONG

At a depth where narcosis can affect your cognitive abilities, Ella changed the dive plan, and Rubin didn’t stop her. When she started to become entangled, she forgot her training and turned when she should have just stopped and backed up.

WHAT THEY DID RIGHT

Rubin correctly handled a tangled-buddy situation. After extricating themselves from the kelp and finding Ella’s air had run low, they ascended immediately rather than try to relocate the anchor line to ascend.

FIVE TIPS FROM THIS INCIDENT

1. BE CAUTIOUS before deviating from your dive plan, especially when narcosis might affect your judgment. It’s always acceptable to be more conservative than planned, but being less so can lead to problems.

2. DON’T TURN AROUND if you become entangled. Stop and slowly back up; that will usually clear you. If not, signal to your buddy for help.

3. KELP DOESN’T CUT easily, but it usually snaps if you bend it sharply, like a celery stalk.

4. IF YOU HAVE A PROBLEM, stop, breathe and think, then act. Remember what you were taught.

5. YOU CAN’T BREATHE WATER, so never risk running out of air. Ascend with a reserve, even if it means a long surface swim or signaling the boat for pickup.