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  • The Scenic Splendor of a Drift Snorkel
    by Tammy Peluso
    The majority of snorkeling adventures, especially for beginners, occur over shallow reefs in calm water. Much like a trek through the mountains, a forest or along a beach, these allow plenty of time to mosey about, identify fish and look at all the small things. Drift snorkeling, on the other hand, is a completely different type of experience. Carried along by the force of the sea, it's more like a scenic car ride, where you sit back and enjoy the scenery.

    Although it often appears there are no currents at all on many reefs, there is always some movement of water as the daily tides rise and fall-the exchange of old water for new is essential to the reef's survival. Local currents are an integral part of every ocean environment, providing the reef with a perpetual supply of plankton-free floating plant and animal organisms. The earth's major oceanic currents bring vital nutrients from the depths of the ocean floor to the surface and transport species, in larval form, among reefs, islands and continents.

    As on land, life in the sea begins with plant matter called phytoplankton. These simple plants have no roots, leaves or stems yet they contain chlorophyll, which enables them, through a process called photosynthesis, to convert the energy of the sun into organic compounds-the base of the food chain that supports all ocean life. Small animals called zooplankton feed on phytoplankton as do the larvae of many fish and invertebrates; small fish and some large ones feed on zooplankton, larger fish feed on smaller fish and so on.

    Quite often currents are strongest off points of land and along the outer edges of reefs. They are often characterized by sheer or sloping walls such as those found off Cancun and Cozumel. Like wind, currents are deflected by solid mass. Strong currents also occur when channels become narrow; the water gains force as it is funnelled through narrow passages. Fiji's famed Somosomo Strait is a prime example: more than 20 dive sites, both wall and lush coral gardens, are scattered along the Rainbow Reef, which lies perpendicular across the channel. Whether you are a diver or a snorkeler it doesn't take long to recognize that the richest reefs occur where the currents are strongest.

    Most noticeable on the underwater landscape are the corals, members of the phylum Cnidaria, appearing in myriad colors, shapes and varieties. Although corals appear as a single unit they are in reality massive colonies of individual animals ranging from a foot across to the size of a pinhead; calcium secretions cement the animals together. Each individual animal is equipped with a mouth surrounded by feathery, sticky, stinging tentacles that trap zooplankton. The animal retracts the tentacles to bring the food into its stomach. Tiny algae called zooxanthellae live within each coral polyp and, through photosynthesis, produce organic compounds that are beneficial to the coral. Because zooxanthellae require sunlight, coral reefs are most prolific in shallow water.

    On many reefs, especially the Caribbean, reef building stony corals such as Star and Brain often dominate, blanketing flat rock surfaces and huge boulders. Other corals such as Staghorn, Elkhorn, Leaf, Tube and Fire create their own unique structures. Gorgonian corals such as seafans, seawhips and searods, members of the class Anthozoa, are plant-like in appearance, appearing as giant fans, thin whips or supple rods. The structure of gorgonians consists of needle-shaped calcareous spicules and a flexible substance called gorgonin, which enable them to bend and bow to the ocean breeze like trees.

    Soft corals of the order Alcyonacea are unique to the Indo-Pacific region. These neon colored, broccoli shaped corals form amazing kaleidoscopic forests. Their expandable, elastic bodies, reinforced with calcareous spicules, fill with water and resemble inflated balloons when they feed. Sponges, belonging to the phylum Porifera, are another major component of the reef scenery. Sponges range in size from small tubes to giant barrels and feed by pumping water through their porous, spongy tissues and extracting plankton from the water.

    Although it's often difficult to stop and identify reef fish and invertebrates while drift snorkeling, it's easy to spot larger fish that feed in the open water and smaller fish that are plankton feeders such as damselfish, wrasses, grunts, bass, squirrelfish, cardinalfish and Anthias (a.k.a. Fairy Basslets), commonly seen hovering in dense colorful clouds over soft corals. Fish that feed on plankton are efficiently designed with streamlined bodies and forked tails, which enable them to battle the plankton rich currents and quickly escape from predators; they always face into the current in order to filter food from the water with minimal effort.

    A completely different cast of characters can be found cruising the blue water wilderness along the outer edge of the reef. Typically, you will see critters of a larger variety: predators such as sharks, jacks, tuna and Barracuda, which feed on other fish, and filter feeders such as whales, manta rays and Whale Sharks, which feast on massive quantities of plankton, Krill and tiny baitfish. Because plankton thrive in shallow water and strong currents, big critters are often encountered while drift snorkeling.

    Currents are somewhat predictable, typically varying in proportion to the size of the tides, however, it is not uncommon for the current to suddenly reverse direction or be still when it should be roaring. Mother Nature has a mind of her own, so it's always best to be prepared for anything. The speed of a current is measured in knots, with one knot being relatively mild and three knots being about the strongest a snorkeler or diver can safely venture into. An easy way to gauge the strength of the current is to watch the soft corals; if the current is mild they will be fluttering, if the current is raging they will be severely bent over.

    In even the mildest current it is virtually impossible to stop unless you hold onto something or exert a great amount of effort. Remember, never touch or hold onto coral; the polyps are extremely fragile and can be damaged easily even if the tentacles are not extended. The best way to enjoy drift snorkeling is to go with the flow and enjoy the reef from this uniquely different perspective.