Cold water wreck diving demands certain considerations, aside from standard warm water wreck diving procedures. Selection and adjustment of equipment such as drysuits and double tanks need extra care. Supplemental mental training is also required for the diver to fully appreciate the adventure.
For great wreck diving, the colder the water, the better. Warm water wrecks may boast great visibility and colorful encrusting corals and sponges but the phantoms of the colder climes harbor great artifact surprises and are usually more intact! You can find warm water exceptions, such as Truk Lagoon, which has mindboggling “in the same condition as they sank” wrecks – but this is unusual.
The mid and north Atlantic waters, the Great Lakes and the West Coast offer many fabulous wrecks. To see these gems you must contend with cold water.
Cold water wrecks tend to have sunk under duress, while still in use, so they go down with “all parts.” Recently, warmer water dive areas have stripped aging hulks and purposely sunk them to create artificial reefs. While interesting dives, stripped ships don’t have the authenticity of a vessel underway that goes down in a storm. Diving a turn-of-the-century wreck in Lake Superior, you can enter the engine room and read the machinery gauge numbers. While diving at about 100 feet, I have seen whole magazines in a vessel’s bunkroom, despite the ship’s entombment in Lake Michigan since the late 1930s.
If you have the opportunity to attempt cold water wreck diving, give it a try. Take consolation by reminding yourself that water freezes at 32 oF – more or less – so it can’t get any colder underwater than that! There are some special considerations when wreck diving in colder waters, in addition to standard warm water wreck diving procedures.
Colder water is typically not as clear as warm water. There may be thermoclines and algae bloom layers that affect visibility at certain depth ranges. It is not uncommon for the surface to have moderate visibility, followed by a band of green, low visibility water. Then, near the bottom, the visibility opens up and exceeds the surface visibility. Horizontal visibility is commonly better than vertical visibility.
Understanding that visibility changes through the layers of the water column could affect your decision to dive on a particular day. Once anchored into a wreck you might look at the pea soup on the surface and be tempted to skip the dive. Persevere! Use the anchorline to descend. You may be wonderfully surprised, midway, to suddenly see a wreck pop out of the haze.
If very low visibility tends to disorient you, always descend and ascend on a line. Make a conscious effort to be in control of your breathing, with slow, measured inhalations and full exhalations. Focusing on your breathing will help reduce your potential anxiety level. It may also distract you from the visibility problem, until you are nearly out of the band of soupy water.
Another trick is to move down an anchorline, hand-over-hand, with your eyes shut. Pop them open for a peek every few breaths. Most people know they shouldn’t be able to see anything with their eyes shut, so it doesn’t seem as scary as having your eyes open and not being able to see. Don’t leave your eyes shut for long periods or you may run into other divers on the line or the wreck or miss a safety stop on ascent!
The best wrecks tend to be deeper. The vessel needs to be below the depth at which it would be torn up by waves, surge and ice floes. Good fathometer readings will show the depths of the wreck’s highest deck and the bottom. Because depth decreases bottom time, it is imperative to plan your dive’s maximum depth. Then, the toughest part is sticking to the plan. It takes strength of character to plan an 80 foot dive and then, after some time at 80 feet, resist the urge to cruise down to 110 to take a closer look.
Cold water has been cited as one of the factors contributing to the risk of getting the bends, even within the limits of the decompression tables. It is foolhardy to push the depth and time limits of the tables, especially in cold water.
You may need a drysuit to be comfortable. It is tough to have fun when you are cold. If you plan to dive more than once in cold water, invest in a drysuit and appropriate thermal undergarments. It is very important the suit seal properly and stay dry. It is not only a matter of comfort but also of safety. If a drysuit floods and the undergarments soak up gallons of water, it is difficult to move.
For the same reason, it is important not to puncture the suit. Jagged, sharp metal edges can pierce drysuit materials. Wreck divers and photographers have a tendency to crawl on their knees, which wears holes in a suit. Many veteran wreck divers wear kneepads or cloth jumpsuits to protect their drysuits.
Equipment can also cause wear. If you have a reel and line that constantly rub against your leg, they can cause problems. When washing your suit, watch for shiny spots and consider adding a protective layer where rub marks appear. Weightbelt buckle upper edges and keepers are other common rub points.
If you are diving in very cold water, you will likely wear one-quarter inch, three finger mitts, rather than thin, five finger gloves. Your dexterity drops markedly with three fingers bunched together. Add to that the numbing effect of cold on extremities and your finger dexterity is severely degraded.
You can plan around the problems to a certain extent. First, don’t use any small clips, especially swing gate snap hooks (known among wreck divers as suicide clips). Many divers place these clips on weightbelts to attach goodie bags or lights. Unfortunately, other things get caught by accident and are impossible to undo in tight quarters, while wearing a thick neoprene mitt. Anchorlines and floating cables inside wrecks are notorious for getting jammed into snap hooks and trapping divers. If you must have a clip, use either brass snaps in which the slider gate is pulled up manually against a spring tension or a stainless steel locking carabineer with a large gate. Avoid aluminum carabineers, which corrode in saltwater and ultimately fail. Place the clip on the piece of gear and snap it into a D-ring attached to your body.
Select all of your equipment with reduced manual dexterity in mind. For example, select a knife with a thick handle for a better grip. Select a light with a large switch you can operate with one mitted hand. Make sure the purge button on your regulator is big enough to operate with a fat finger. Try to eliminate any round snaps – they are nearly impossible to close with cold, mitted hands.
Third, adjust every piece of equipment before you get into the water. Adjusting a mask strap using mitted hands is nearly impossible. In cold water, who wants to voluntarily take off a mask to make an adjustment that could have been done on the surface?
For safety, most wreck divers use double tanks and many add a small pony bottle for emergency use. When deep diving in cold water, your air consumption increases and the double tank volume adds a safety factor. Penetrating a wreck forfeits your vertical avenue of escape and survival depends on an adequate air supply. There are two schools of practice for regulators. One camp yokes their tanks together and uses a single first stage with a primary and secondary second stage. Others put a separate regulator on each tank. The pony bottle always has its own regulator, which is distinguishable from the main air supply second stage and is attached so it is reachable from any position.
One of the greatest dangers of wreck penetration is silt. This combination of rusting (iron and steel) particulate matter and microbial destruction of organic (wood, fabric, etc.) ship parts is everywhere – ceiling to floor. It can be several feet deep.
Drysuit divers need to take extra care to be neutrally buoyant and trap the least volume of air inside their suits. This can be a challenge. Too much air in a drysuit increases your overall measurements. It means you will brush into more things from sheer size and from being somewhat rolly polly and less stable. Bumping any surface or kicking your fins can stir up silt and destroy visibility inside a wreck.
Move through a wreck by attaining a near horizontal body position, folding your legs up behind you and propelling yourself by “walking,” using one finger to push yourself along. This will dramatically reduce problems from silt. You will also notice you get cold quicker, because you are getting the least exercise possible! While congratulating yourself on not stirring up the silt, don’t linger in one place too long or you will discover descending silt. This consists of overhead particles dislodged by your rising bubbles.
Cold water wreck diving has outstanding rewards for divers who want to see largely intact wrecks. These pieces of history are scattered along the cold water coasts and in the Great Lakes.
Once equipment is selected for cold water comfort and usability, you can plan safe dives. Most divers find the more arduous conditions add to the adventure and are not as macho as they might have imagined.
The minimal intrusion techniques used in wreck diving can be adapted to no-impact reef diving as well. Safe and enjoyable cold water wreck diving begins with a well thought out dive plan and proper equipment and concludes with the execution of that plan.
This article discussed some of the differences and considerations in cold water wreck diving. It is important to remember these are in addition to standard wreck diving procedures and practices. Wreck diving is a challenge – from library research to learn a ship’s history to executing a deep, cold dive far offshore. It is an advanced activity that requires supplemental training and equipment – but more than justly rewards you when the secrets of history are revealed in person.