Sandy bottoms and life off the reef

When I was a newer diver, I was afraid to leave the reef and swim out into the sand beyond.

Throughout my dives, I would swim right along the edge of the coral and look out into the blue. It was ominous, almost like a desert. I wasn't sure how to navigate once I left the familiar natural features of coral and rock. And, I didn't know what to expect out there! What creatures would I find, and would I find any at all? Might I waste an entire dive just looking at the bottom?

The truth is, that sand and grass bottoms can have just as much interesting life as the nearby coral reef! You just have to know how to plan your dive, and what to look for!

As divers, safety is always our top priority. Before exploring a new environment, double check that you and your buddy are both completely comfortable with the plan. And, make sure you have the right tools to make the dive both safe and fun. In this case, you should carry a compass and know how to use it properly. You should also double check that your buddy team has no buoyancy issues. When diving over sand, even a few fin kicks to the bottom can seriously reduce your visibility. It is a good rule to remain around one meter from the bottom so as not to disturb the sand.

The compass can be an extremely helpful tool, but only when properly used. It is vital that you wear or carry your compass with the window facing you, and try to keep it relatively level and horizontal at all times. And remember, you MUST use a compass heading when you are swimming out from the reef. If you do not know what direction you swam from, the compass will do you no good in finding your way back to the starting point. Additionally, choose a major landmark from which to leave the coral. I like to find a large fan, pinnacle, or very memorable coral head to start from. This way I can be sure to re-enter the reef at or near my starting point. You should choose a compass heading that takes you out of sight of the reef, and keep your depth in mind! There is no need to swim far, especially until you are more comfortable and familiar diving over sand. To properly select a heading, choose a direction in which to swim. Then, turn the bezel on your compass until north is in the index marker. Take note of what number falls on your lubber line, as this is your heading. Remember, you will need to swim the exact opposite heading to return to your starting point. As you swim, keep track of your time, or distance using kick cycles so you will always know how far you are from your entry point.

When you first leave the reef, keep your eyes open for patches of sea grass or lone coral heads as you transition into the sandy bottom. These natural features offer great hiding places for smaller marine life out in the sand. You may want to take your time and hover over these for a bit. Because these habitats offer less natural shelter, the organisms that thrive here are masters of disguise! Turtle grass is an especially good place to look for seahorses and their close relatives. The sand just around a lone patch of grass or a coral head is a great place to look for ambush predators such as stonefish and scorpionfish. They lie here in wait for small fish entering and exiting these safe havens.

Sandy bottoms are also a good place to hunt for tube dwellers such as gobies and blennies. As you scan the bottom, search for small holes. Here you may find a variety of animals hiding out in tunnels besides those that you are looking for! Many species of gobies share their home with a small shrimp. Also, an open tunnel is a fair opportunity for just about anybody to move in. You can also look to these small holes to find jawfish and mantis shrimp.

Snake eels and garden eels are also interesting sand dwellers. The snake eel periodically leaves its home to hunt or relocate, and does not actually dig itself a tunnel. It simply burrows through the sand or mud bottom to make its home. Garden eels live similarly, but are typically found in large colonies. Best viewed from a distance, garden eels are quite shy and will typically duck into the sand as divers approach.

The sandy outskirts of the reef also offer the perfect home for rays, flounder, and other odd bottom dwellers. You may also encounter some species of puffers. These animals all use the sandy bottom for camoufloge, and can be quite hard to spot. You can try to look for irregularities in the patterns of the sand, or you can just hover in place for a few moments and see if anything moves! Sometimes you might be surprised by what was right beneath you.

Small sandy patches in the reef can also host many of these species, so don't pass them by on your dives! Remember to dive responsibly, and to carry a compass if you are diving in an environment where natural navigation is not reliable.


@ This article above is written by Jessica Merrill (PADI Instructor #351781), please give respect to her copyright!
This article is not allowed to be reproduced or distributed without written permission of Jessica Merrill.

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