Diving underwater isn’t simply for leisure; it’s a vital profession with various industrial uses. Commercial divers are brave professionals working in hazardous conditions. Most divers focus on a specific type of underwater task, with the highest pay going to those who dare to face significant health and safety challenges. Here’s a look at some of the most intriguing (and often repulsive) jobs that commercial divers handle.
10. Underwater Welding

Welding metals underwater may seem like an impossible task, but it's actually one of the most valuable skills a commercial diver can learn. The method of joining metals underwater originated in the 1930s and is commonly used to repair submerged structures such as bridges, ships, and pipelines.
Underwater welding has two main types: dry and wet. Dry welding, the more frequently used method, involves a hyperbaric chamber that seals the welding area. Water is pumped out of the chamber and replaced with a gas mixture of helium and oxygen. Offshore projects like those on oil rigs use 'habitat welding,' where the gas-filled chamber is large enough to accommodate multiple divers. Helium and oxygen are pumped in while toxic welding gases are removed, creating a dry, breathable environment for work.
Wet welding is considered far more hazardous due to the fact that saltwater is an excellent conductor of electricity. Wet welders often rely on a method known as shielded metal arc welding, which creates a protective layer of gaseous bubbles around the weld area to shield them from electrocution. Despite taking proper safety precautions, both wet and dry welders face dangers like electrocution, explosions, and drowning. It's not a job for the faint of heart—or lungs.
9. Sewer Diving

Sewer systems in major cities are complex networks with numerous moving components. Hundreds of pipes and pumps are responsible for flushing away the city's waste, and they often become blocked with a variety of undesirable materials. This is when a sewer diver comes into play. Julio Cu Camara has spent nearly 40 years diving into the sewers beneath Mexico City to maintain the intricate drainage system that ensures the city remains clean. Dressed in a hermetically sealed dive suit that's just three centimeters thick, Cu makes regular dives into the black waters to perform vital maintenance on motor parts.
Julio can repair pumps in a single day that would normally take two weeks to fix. And did we mention that he does it without sight? The 'black water' is not a mere metaphor—Mexico City's sewers are so contaminated with human and chemical waste that no light can penetrate the murky depths. As Cu grows older, he’s training a successor to continue this crucial work when he retires. The next sewer diver will not only have to endure the overwhelming stench but also get used to occasionally encountering the bodies of dead animals—such as horses or pigs—floating through the sewers without wondering, 'Who flushed that?'
8. Aqueduct Repair

New York City's water supply is drawn from reservoirs in the Hudson Valley and Catskill Mountains, which are connected to the city by massive tunnels like the 85-mile-long Delaware Aqueduct. In the late 1980s, the city noticed leaks in the aqueduct and hired a Seattle-based diving firm to investigate. In February 2008, a team of divers was sent into the depths of the aqueduct, where they spent two weeks living in a sealed, pressurized chamber equipped with sleeping quarters, toilets, and even a Nerf basketball hoop. To safely navigate the high-pressure underwater environment, the chamber was pressurized with a mixture of 97% helium and 3% oxygen, which allowed the divers to avoid decompression sickness, also known as 'the bends.'
Divers worked in 24-hour shifts, being lowered 700 feet into the shaft to inspect the structure and take measurements for repair equipment. Later in the year, the city sent divers back into the aqueduct to fix the valves at the bottom of the shaft, where they stayed for nearly a month. After their time in the pressurized chambers, the divers had to slowly wean themselves off the helium over the course of a week to readjust to normal surface air. Diver Chris Hackworthy recalled that one of the toughest challenges was communicating in the helium-filled environment, which made everyone sound like Alvin and the Chipmunks. Since helium also dulls taste buds, the crew survived on spicy foods like Tabasco sauce and jalapeños during their time underground. One can only imagine how much they relied on the fans in the bathroom, since Febreze likely wasn’t on the packing list.
7. Nuclear Diving

Nuclear power plants require vast amounts of water for both electricity generation and hazardous waste management. When maintenance is needed for their water systems, plant managers call on nuclear divers. Many of the tasks performed by nuclear divers are low-risk, such as 'mudwork'—cleaning intake pipes in lakes that supply water to the plant. These pipes often get clogged with debris, including fish that mistake the plant’s warmth for breeding grounds. While cleaning fish remains from large pipes is unpleasant, it’s not a risk to the divers’ radiation exposure. However, when divers repair underwater carts used to move spent fuel rods from reactors to storage pools, they must carefully monitor their radiation levels.
During longer dives in high-radiation zones, divers sometimes find their dosimeters indicating exposure beyond the acceptable limit. When this happens, plant managers must decide whether to send in a replacement or allow the diver to exceed the legal exposure limit. Nuclear divers often say that the real concern isn’t a single, high-level exposure, but rather cumulative small doses over time, which can have unpredictable long-term health effects. As the spouse of one diver said in a Popular Science article, 'Who wants a glowing husband?'
6. Discovering Lost Civilizations

Though the legendary city of Atlantis remains undiscovered, underwater divers have uncovered some truly remarkable archaeological treasures. While many associate underwater archaeology with shipwrecks, that's just one category among many that divers explore. Over time, coastlines shift, and regions once above sea level are now submerged. These ancient underwater sites include Neolithic villages like Atlit-Yam in Israel and more recent coastal towns such as Port Royal in Jamaica, which once thrived as a colonial settlement. In 2020, archaeologists surveyed an area off the coast of Murujuga in northwestern Australia, discovering 269 stone artifacts with the help of scuba divers. Radiocarbon dating revealed that these artifacts, believed to be tools for scraping and cutting, were between 7,000 and 8,500 years old. One of the items found was thought to be a grindstone used to crush seeds into flour. This site marked the discovery of the first submerged site over 5,000 years old in the tropics, demonstrating that stone tools can withstand the conditions of warm ocean floors, despite the challenges posed by algae and natural disasters. These underwater archaeology projects remind us that pieces of history can be hidden in the most unexpected places beneath the surface.
5. Finding Drugs

People often stash drugs in bizarre places, but hiding them in the ocean is a whole new level of boldness. In 2020, volunteer divers working off Florida’s Treasure Coast stumbled upon a square package floating in the water. When they opened it, they found a kilogram of uncut cocaine, which they promptly handed over to the Coast Guard. This wasn’t the first time drugs had been found off the Treasure Coast, and locals have a nickname for these floating packages: 'square groupers.' It’s believed that drug dealers toss their contraband into the ocean when they sense danger of getting caught. In April 2021, a much larger drug cache was found by the Greek coast guard. Acting on a DEA tip, coast guard divers discovered 46.7 kilograms (about 103 pounds) of cocaine hidden behind a grate in the hull of a cargo ship arriving from Brazil. The operation led to the arrest of 23 crew members involved in the trafficking attempt. As for the local fish, no reports yet on whether they started swimming a little faster.
4. Cleaning Oil Spills
The British Petroleum oil spill in the Gulf of Mexico stands as one of the most devastating environmental disasters in American history. Along with commercial fishermen and Gulf Coast residents, one of the groups hit hardest by the catastrophe were the divers sent in to assist with the cleanup. Despite the overwhelming presence of carcinogenic crude oil in the ocean, BP's health and safety experts assured the divers they didn’t need any additional protective gear. Cleanup teams labored up to 20 hours a day in the toxic waters, and many divers began falling ill even before the operation was completed. The crude oil itself was a major hazard, but the dispersants used to break down the oil likely exposed the divers to additional dangerous chemicals. These dispersants were banned in the United Kingdom years ago due to their harmful health effects. Since the spill, nearly all of the divers involved have reported health issues, and at least two have tragically taken their own lives. In 2010, around 700 commercial divers filed a class-action lawsuit against BP, which remains unresolved to this day.
3. Searching for Lost Cheese

In a quirky tale from 2005 that could be aptly named À la recherche du fromage perdu (In Search of Lost Cheese), a French-Canadian cheesemaker enlisted the help of professional divers to recover 800 kg (about 1,763 pounds) of cheese he had accidentally dropped into a lake. Luc Boivin, from La Fromagerie Boivin in Quebec's Saguenay region, had placed the cheese underwater deliberately, believing that aging it in the lake would infuse it with a unique flavor. However, he didn’t secure it properly, and a year later, the cheese was nowhere to be found. A team of expert divers scoured the Saguenay Fjord using advanced tracking equipment, but after an extensive search, the effort was ultimately called off. Boivin, worried that continued funding of the search would exceed the 50,000 Canadian dollars the cheese was worth, decided to cut his losses.
The cheesemaker’s unusual aging experiment was inspired by an earlier incident when a fisherman discovered a block of Boivin’s cheese in the lake, and declared it to be the best he had ever tasted. Perhaps the cheese was so extraordinary that the divers decided to help themselves and didn’t report it. After all, they've certainly earned a treat for all the challenging and often unpleasant work they endure.
2. Sewage Diving

If the tale of the sewer divers was a bit too much for your stomach, you may want to skip this one.
For those of you still here, you might be wondering why we have another mention of diving in sewer water, especially when we've already covered it. That's because there's an even more unpleasant job than sewer diving: diving into liquefied, undiluted waste. Rather than the typical sewer systems, professionals like Austrian diver Gregor Ulrich work in wastewater treatment plants, where they are sent into massive digestion towers brimming with sewage sludge.
At treatment facilities like the Winterthur waste plant, these towers are engineered to treat the sludge with the help of aerobic bacteria powered by compressed air blowers. The sludge is then transferred to larger anaerobic towers where it generates methane gas. This creates an extremely flammable atmosphere for the divers, who are tasked with maintaining these towers while gas levels are closely monitored to prevent explosions. To add to the discomfort, the sludge is kept at a temperature of around 37°C (98.6°F), which makes it feel like swimming in warm mud. Ulrich claims he prefers it to cold-water dives. His supervisors must be relieved he feels this way, as employing divers saves the plant significant amounts of money compared to halting operations and emptying the tower for each cleaning.
1. Exploring Icebergs

You may have heard of cave diving, but what about diving inside a floating ice cave? This is exactly what professional cave diver Jill Heinerth and her team did in 2019, marking the first-ever dive into the crack of an iceberg. During their descent, Heinerth and her diving partner were bombarded by falling isopods, a type of cold-water crustacean that she described as ‘horror story material.’ The adventure took a more terrifying turn when they attempted to leave, only to find their exit blocked by large chunks of ice that had fallen off the iceberg. After some struggle, the divers managed to make a hole large enough to squeeze through, but their ordeal was far from over.
On their next dive, a powerful current began pulling the divers toward the iceberg, as if the frozen mass was trying to draw them into its icy core. Instead of resisting the current, they decided to let it guide them away from the exit and toward a different light source, which seemed to offer another potential escape. When Heinerth surfaced, she discovered that their boat had vanished, swept away by the same current that had pulled them into the iceberg. Eventually, the boat's crew managed to locate the divers, and they narrowly avoided disaster once again.
On the third dive, Heinerth took two more divers into the iceberg. After descending into the crevasse, she immediately realized the current was far too strong, signaling her team to retreat. However, once again, they couldn’t find a way out. Struggling against the current to return to the exit, they encountered another obstacle: water was pouring into the crevasse, preventing them from climbing back. Thinking quickly, Heinerth devised a plan to scale the crevasse wall, using small gaps in the glacier as footholds. After climbing 130 vertical feet of ice, she turned to her team and solemnly remarked, 'the cave tried to keep us today.'
