“DSV Depth Charge, this is R/V Taprobane, do you read?”

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By 6:00, the Depth Charge had moved off. Upali watched it aim for Batticaloa harbor, exhaust trailing behind. “Fresh air…” he murmured, shaking his head. Ranjith guided the Taprobane into position for their search, his eyes on the GPS screen, hands on the wheel and throttle.

Shipwreck hunting has a romantic sound to it, largely thanks to tales of Caribbean treasure hunts and Clive Cussler novels, but in reality, it is stupefyingly boring. The first step is to identify anomalies on the ocean floor, those features that don’t appear to be naturally occurring objects such as rocks, coral heads, or schools of fish. This is done by dragging a side-scan sonar device behind the boat in a systematic pattern, a process known as “mowing the lawn” and is just about as exciting as walking up and down a suburban backyard. The sonar device, known as a tow fish, is shaped like a torpedo, with a cylindrical body and stabilizing fins at its back end. As it moves through the water, the tow fish sends audio pulses into the depths, which bounce back off the sea bed. This paints a sort of electronic picture of the terrain on a laptop screen on the boat. Man-made objects, usually shipwrecks or pieces of debris, are recognizable by their more geometric shapes on the screen. Right angles and straight lines rarely occur in nature. These anomalies are marked with GPS coordinates to be investigated more thoroughly later with the ROV. A day spent mowing the lawn under the tropical sun, watching a computer monitor for anomalies, is only tolerable with the promise of actually finding something, which rarely happens.

A few weeks earlier, a fisherman had snagged his line on what he assumed was a rock ledge and pulled up a faded orange life ring with some indistinguishable writing on it. A shipwreck? That would explain the good fishing. Fish tend to congregate around wrecks for their relative shelter on barren sea floors, but there were no known wrecks in this area. Word got back through the fish market gossip, on up to a local politician, who alerted the naval base in Trincomalee. The navy didn’t have the time to go on wreck hunts, so it passed the message on to MOCHA’s offices in Colombo, and that’s how Upali Karuna found himself slowly motoring up the coast on the Taprobane on this cool morning.

After an hour and a half of mowing the lawn, the MOCHA team decided to investigate a promising anomaly from the sonar scans, a long shadow on the slope of a deep ocean trench that slashes in from the continental shelf towards Batticaloa. Here the sea deepens from 150 feet to over 300 quickly, and then drops over a precipice into 2,000 feet of dark water.