Category: Travel

Light

The speed of light is the absolute fastest limit that anything can travel in our universe. Its speed is assigned the constant c, as in Einstein’s E=mc^2 fame. Its declared speed of 186,282 miles per second is achievable only in the empty vacuum of space. Any medium through which light passes will slow down its velocity; some enterprising and possibly bored scientists have in fact managed to slow light down to 38 miles per hour by beaming it through a cloud of super cold sodium vapor. The ratio of c to the velocity at which light travels in a transparent medium known as its refractive index. This index of refraction is also an indication of how much the propogation direction of light changes as it enters or exits a transmission medium. This can be seen in the everyday phenomena of dipping a broom stick into a swimming pool and having the broom stick appear to bend at an angle as it enters into the water. This refractive property of transparent materials gives us lenses that bend light allowing the construction of microscopes and telescopes. All this theory is most easily summed up as light changes speed and direction as it enters and exits different materials.

Water

Things that are less dense float above things that are more dense. Fresh water can float on top of sea water because the salt in the sea water has brine denser. That is why you float easier in sea water than in fresh water. The cenotes along the Riviera Maya peninsula discharge enough freshwater into the Caribbean Sea to visibly affect the salinity of  the seawater. On calm days, when the outflow from the karst formations is not induced by wave action to mix with the sea water, the freshwater stratifies itself above the denser seawater. The boundary layer between the salty seawater and the less salty freshwater is called a halocline. Ironically, and contrary to scuba divers’ experience, the thermocline at this salinity boundary is reversed with the solar warmed seawater lying below the cool waters just discharged from the sunless cenotes.

Halocline

Some two and a half feet below the surface of the Caribbean Sea at Tankah Bay, Mexico lies the undulating boundary between saltwater and freshwater. This boundary is visible as shimmering layer of water, similar to what cooking oil floating on top of water in a container might look like. This halocline is visible due to the different refractive indices of saltwater and freshwater.

Swimming on the surface, the submerged halocline can be seen as a glassy underwater layer, wavy like antique window panes before the perfection of modern flat glass manufacturing technique of floating molten glass on top of a sheet of melted, liquid tin. The visibility of the halocline is due to its refractive properties and how light bends as it crosses the freshwater to saltwater boundary.  Since the halocline was relatively shallow, it was easy to dip a hand or arm through the boundary layer while finning along on the surface, resulting in a visible plume of disturbed saltwater, like a cloud of fine dust kicked up by a car driving on a rural dirt road. Both the temperature and salinity differences stayed distinct within the region of disturbed water and did not homogenize, leading to an effect of veins of saltwater wrapped around veins of freshwater, forming a visual cloud of waters having two different refractive indices. Diving through the halocline resulted in being surrounded by an indistinct cloud of the disturbed halocline waters. Within the cloud, being made up of a weave of tendrils of different refractive indices, it was impossible for eyes to focus. It was very much like a dive mask fogging up completely. Actually, the first couple of times this happened to me, and before I realized what was going on, I did think that my mask had fogged up or somehow suffered a failure of some sort.

Drifting within the cloud, and concentrating on focusing and making sense of the visual field, the impression was that the cloud was made up of a grid of whorls of haloclines. It was actually somewhat indescribable. Only the limits of my breath holding capacity forced me to come up from this submerged playground.

This was a most unexpected, and most unique swimming experience, and I spent much time playing with the halocline boundary layer, just to watch the almost magical show that would emerge.

There’s a backcountry skiing culture that can be seen on the traverse over the Continental Divide in Colorado. At intervals along Loveland Pass, parked in clusters along the lonely mountain road are cars, vans, and trucks, seemingly abandoned with no signs of the occupants, and no establishments for their patronage to explain the absence of the vehicle occupants.

The practice of skiing in the backcountry at Loveland Pass is to pull over at a spot having access to a skiable slope of the Divide, and hop on the slope from the side of the road. At the bottom of the ski run, the skiers will either hitchhike or have a friend with a vehicle to ferry the skiers back to the top of the mountain.

There’s an outlaw, renegade air about parking at where your heart desires, and just hopping off the side of the road and making a ski run down the side of an unmaintained, public mountain slope.

Such was the diving in Bonaire. Most of the named dive spots lining the divable western side of Bonaire island are accessible as shore dives. Along the roads that run along the undeveloped coastline can be seen pockets of pickup trucks seemingly abandoned on the many crushed coral beaches. The trucks being well worn, with spots of rust lent the scene that lawless feel.

Being divers ourselves, we followed the local custom of dumping our rental pickup truck wherever there was a dive spot, then donning our scuba gear and wading into the surf to dive, leaving our trucks on the beach unmanned, unlocked, and with the windows open. We had been warned, and there were stickers in the cars requesting “Divers/snorkelers! Help prevent break-ins. Leave your windows down and doors unlocked! Do not leave valuables in car.”

My first real dive in Bonaire, not including the check-out, shake-down dive at the dive resort’s house reef, was Oil Slick Leap. As an introduction to diving in Bonaire, it was unparalleled. Access to the water was both easy and dramatic. After parking in the parking area, it was a short walk to the edge of the island, followed by an eight foot jump into the water; a ladder was permanently affixed conveniently nearby for coming back to land.

Bonaire diving was uniformly good. Great visibility in warm waters with no perceptible thermocline. It is widely known for its abundance and variety of sea-life. Southern dives are characterized by a double reef, whereas dives on the northern end of the island had just a single reef wall. Almost all the dives there followed the same prototype: a shallow rocky, sandy shelf extending anywhere from ten to over a hundred meters from shore, followed by a reef wall that bottomed out at at depth of about thirty feet. On the double reefs, the sandy bottom between the two parallel lines of reefs have a depth of a little over a hundred feet; at the drop-off of the outside reef, the wall could go down to over five hundred and fifty feet.

While most of the diving was similar in nature to each other, two stand out: the two hundred and forty feet length Hilma Hooker wreck, and the Salt Pier night dive.

Hilma Hooker‘s demise in Bonairean waters occurred in the summer of 1984 when she docked at the Town Pier with rudder troubles. Suspicions were raised when her captain was unable to produce her registration papers. She was boarded and discovered to be carrying 25,000 pounds of marijuana hidden behind false bulkheads. The crew was detained and the ship was held as evidence while the authorities attempted to locate the ship’s owners, who understandably never stepped forward to reclaim her. The ship, due to her poor upkeep, soon began to take on water. Fearful that the ship would sink at the main dock disrupting maritime traffic, she was towed and anchored at the Southern part of the island. On 7 September, 1984, the ingress of water overwhelmed the pumps, and she sank in about one hundred feet of water, coming to rest on her starboard side. Unlike intentionally sunk ships that are more correctly called artificial reefs, and which have been stripped and meticulously cleaned to prevent its polluting the environment, the Hilma Hooker is considered a true ship wreck, because with the exception of its illicit cargo, all of her contents had been left in place since the vessel was considered evidence in a developing criminal case. The Hilma Hooker is regarded as a leading wreck dive site in the Carribbean.

Possibly the most spectacular dive experience on Bonaire is the Salt Pier night dive.

The pier is constructed off-shore, forming the end of a conveyor belt that loads salt from the on-shore evaporation ponds to ships moored at the pier. Both the salt works and the pier are owned by Cargill; permission is needed from Cargill to dive the pier, and only when there are no ships moored at the pier; a local divemaster is required to guide all dives at the Salt Pier, which we arranged through our resort. On the night of our dive, we gathered at sunset the resort to meet our dive guide, only to be told that for whatever reasons, and despite repeated assurances from Cargill, the ship docked at the pier still hadn’t left, and wouldn’t leave, so our dive had to be canceled. Our pent up anticipation having been dampened by our disappointment, we nevertheless decided to head out and do a couple of night dives on our own since our dive gear was already loaded on the trucks. We went to a dive site called The Lake, doing the usual ditch the truck on the beach routine, and additionally setting up shore strobes so that we could find our way back to our ingress site at the end of the dive. After the dive at The Lake, half the group wanted to do a second dive; I belonged in the other half of the group who didn’t want to do another night dive. We moved our vehicles up to another dive site that was opposite the airport, and we non-divers promised the diving group that we’d baby-sit the beer, and we assured them that there’d still be beer when they returned. They looked at us suspiciously.

Unlike all the other dive sites we had previously visited, there was no beach parking at this site. We were just pulled over by the side of the road. It was a wonderful night to be sitting out with a beer in hand: the skies were clear, the weather was warm, and there wasn’t much traffic on the road. Being opposite the airport, every once in a while, an incoming plane with its landing lights cutting through the dark would fly its final approach right above our heads to land on the runway that was on the other side of the road alongside which we were parked. The planes weren’t quite as low as the ones at the Princess Juliana airport on St. Maarten, but it felt plenty close enough for us to get a thrill out of being directly under a plane that was to touch down just a few seconds after passing overhead.

The moored ship left the next day, and we did manage to get to do our Salt Pier night dive, which turned out to be one of the most unique dives that I’ve done. The lights on the pier had been kept on, and they blazed in the warm Bonairan night, giving us bands of shimmering illumination and shadows as we swam under the pier. Because the pier pilings were canted with a wider base and meeting at a narrower apex, the experience was like diving within the arches of a shadowy, underwater cathedral. While the other dives were characterized by swimming and covering distance and seeing as much of the reef as possible, the Salt Pier dive was marked by a desire to just staying within the confines of the pier, seeing the sea-life wend their way through the pilings, and watching the play of lights as they shone from the surface through the gentle waves and through the legs of the pier. The Salt Pier night dive would certainly go down as one of the more unforgettable dives for its uniqueness.