Understanding the mammalian diving reflex

The animals that live and feed underwater have developed a method to conserve oxygen and defend against hypoxia when diving under the water. This ability is termed the diving response or mammalian diving reflex (MDR), which controls the constriction of blood vessels in certain parts of the body (vascular constriction) and decreases heartbeat (bradycardia). This was not known to be capable by humans until the 1950s, but was observed by researchers in whales, seals, sea lions, and penguins in the early 1900s.
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Decompression Diving Overview

As your desire to dive deeper and stay longer expands, you leave the realm of recreational diving and the no decompression limits that you were taught. Diving deeper and staying longer at depth moves you into decompression diving. Decompression diving requires detailed planning, preparation, equipment, and mind set and takes you into a very advanced form of diving. If you have the desire to explore wrecks, caves, or whatever that lays in deep water, getting the proper training to safely operate and return from these depths is a must. Before you can return to the surface, you must decompress.

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Lessons Learned!

Are you prepared for the environment you’re diving in?

by Don Reynolds

My best dive buddy, Mike Rowley, lives in Lodi, California. Fortunately, we’re able to get together a few times a year and enjoy the warm waters of the Caribbean. I live in the Northeast (New York), and I’m not real fond of cold water. But Mike had been after me to come to the west coast to do some diving, and I finally relented.

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Drift Decompression Diving

by David Miner

Diver deploying a lift bag on a free ascent decompression drift dive

Standard drift diving is a specialized form of boat diving allowing you to drift with the underwater currents during your entire dive. The boat is never anchored or moored and follows the group of divers the entire time. The different types of drift diving are: float drift and live boat drift. Float drift diving involves the use of a float with a down line or drift line that is towed by the dive leader or divemaster and always lets the boat captain know where the group is. The boat captain follows the float on the surface. Live boat drift diving requires no drift line forcing the boat captain and crew to follow the divers’ bubbles as they drift along.

However, there are also sometimes strong currents on deeper wrecks or other dive sites where you don’t want to drift during the dive, but must drift during your decompression stops on the way to the surface. There are several forms of drift decompressing after the dive is complete, anchor line drift decompressing, float/buoy line decompressing, and free ascent decompressing. Whether drifting for the entire dive or diving a wreck and only drifting while decompressing, there are things to consider and special equipment needed to safely complete your decompressions stops and surface with the boat waiting to pick you up.

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Frequently Asked Questions

What is the definition of spearfishing?

Spearfishing is the act of using a device, such as a speargun, pole spear, or Hawaiian sling to impale a fish underwater and then bring it back to the surface. Fish are generally speared for food, just like deer hunting or any other kind of hunting.

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