Support an exhausted, responsive diver at the surface: self-protection, buoyancy, communication and tow in overview. Practise only in a rescue course.
What do you do when a diver at the surface can no longer make progress? The honest answer: first you protect yourself, then you secure buoyancy, then you talk to him calmly, then you tow him. An exhausted but responsive diver is the most common rescue situation. With a clear sequence it stays a rescue and does not become a second accident.
Exhaustion rarely comes out of nowhere. In an analysis of 126 fatal dive accidents in Australia, environmental conditions were a trigger in 54 percent and exertion in 18 percent [3]. The effort is real: a study of 959 dives estimated the workload at about 5 MET (resting metabolism times five), about as much as brisk walking, and advises fitness reserves for 7 MET [4]. Tired divers often slide into panic: according to the literature, the instinctive reaction to stress underwater is incompatible with diving, for example flight and rapid ascent [6].
A DAN report shows what it looks like: two divers drifted in current under a bridge, could not descend and struggled at the surface; one was at times unresponsive, the other exhausted with cramps. The author of the report, himself the rescuer, pulled the first with a tank tow toward the shore [5]. This guide explains and motivates, it does not replace the rescue course.
Someone making almost no progress, kicking hard and still drifting often looks calm but is not. Watch for sagging shoulders, calls for help, flailing arms or a head lying lower. The US agency NOAA lists "Assist a tired diver" as its own item in its diver checklist, at the surface in water too deep to stand [2]. Milestone: you recognize signs before anyone calls.
DAN says: first make sure you and the diver are safe; watch for current, poor visibility and hazardous marine life. Help from the surface or shore if possible, with a line or flotation device. If you must enter the water, only with fins, mask, snorkel and flotation. Physical contact with a panicked diver puts you at significant risk [1]. Milestone: you keep distance and hand over an aid first.
DAN: establish positive buoyancy, remove weight belts or drop heavy loads, and inflate both BCDs, yours and the diver's [1]. Then nobody sinks and you gain time. Milestone: you float without treading, and so does the diver.
Speak calmly, loudly and clearly. Say what you are doing and what he should do: "Breathe calmly. I am here. We are going to the boat." Make sure his airway is clear. Panic can be managed [6], and a clear, calmly announced plan helps (training practice). Milestone: the diver breathes more calmly.
In overview: there are several tow variants, such as pushing at the forearm or the tow at the cylinder valve. In the DAN case the rescuer had the diver roll onto his back and pulled him in a "tank tow" sideways out of the current, where it was slower [5]. DAN names as principle during transfer: protect the airway, everyone positively buoyant, rescuer stays in control, topside help ready [1]. You learn the technique in a course, not here.
Hand over at boat or shore, check condition, inform first responders. If the diver is unresponsive or not breathing, the situation changes to rescue breathing (see the unresponsive diver guide). Milestone: the diver is safe, the emergency number is alerted.
Avoid the rescue by planning. The DAN report concludes that the rescue would have been unnecessary if the divers had followed basic principles. The author advises scouting the site beforehand, knowing your limits and agreeing on a plan with contingencies [5]. A conversation before the dive costs two minutes. If you are unsure, have the guide or instructor brief you on the site.
He barely makes progress despite effort, sags in the shoulders or flails with his arms. The head lies lower, the voice is calm or panicked. Ask and observe if you are unsure.
Protect yourself and help from outside if you can: line, buoy, boat [1]. In the water: lead off, inflate both BCDs [1].
Only with training. Techniques like the tank tow or arm grip you learn in a rescue course. The diver may panic, and physical contact is dangerous [1].
Plan the site, know the current, keep fitness reserves and signal in time. Workloads around 5 MET are normal, 7 MET is considered the needed reserve [4].
Rescuing an Unresponsive Diver: Overview of In-Water Breaths, Taught Only in a Rescue Course