One of the best ways to make money early in GTA 5 is by collecting nuclear waste and underwater briefcases.
To get started, head to the Sonar Collections Dock off the Great Ocean Highway and purchase the property for $250,000.
Note: You can only purchase the property after completing the Merryweather Heist.
Once you own it, climb into the submersible at the end of the dock and use the Trackify app to locate all 30 nuclear waste barrels around the map. Each barrel earns you $23,000, and collecting all 30 rewards you with an additional $250,000, for a total profit of $690,000 (after buying the dock).
Along the way, you can also find 11 underwater briefcases worth $143,500 combined, bringing your total profit to $833,500.
Note: This side quest requires you to travel around the map in a slow-moving submersible, so it can take two hours or more to complete.
Zone 1
Nuclear Waste #1
The first nuclear waste barrel is just a short distance from the Sonar Collections Dock. Use the Trackify app to follow the red dot, keeping it near the center of the screen until you spot a glowing yellow barrel on the seafloor.
To collect it, simply drive the submersible over the barrel. Trackify will then point you toward the next barrel.
Nuclear Waste #2
The second barrel is close to the first. Follow the Trackify marker, then descend over a small underwater cliff to reach it.
Tip: To descend straight down, hold X (PlayStation), A (Xbox), or Left Control (PC). To ascend straight up, hold Square (PlayStation), X (Xbox), or Left Shift (PC).
Underwater Briefcase #1 ($12,000)
The first underwater briefcase is just off the route to the next nuclear waste barrel. Turn slightly to the east to find a sunken plane.
Head to the tail of the plane, then search the seafloor in front of the fuselage, near its left side as you face it. The briefcase is easy to miss among the plants, so search the surrounding seafloor carefully.
Tip: If the briefcase doesn’t appear, try saving your game, quitting, and reloading.
Nuclear Waste #3
The third barrel is nearby, but it’s easy to miss because it’s tucked behind a rock formation. Approach it carefully and look around the rocks if you can’t spot the glowing yellow barrel right away.
Zone 2
Nuclear Waste #4
The fourth barrel is a long way from the previous one, and you can’t follow the Trackify marker directly because the coastline gets in the way. Use your map to navigate around Paleto Bay, then descend to a depth of 440 feet to find the barrel.
Tip: Turn on the submersible’s lights to see more clearly. Press Right on the D-pad (PlayStation and Xbox) or H (PC).
Nuclear Waste #5
The fifth barrel is nearby and is the first one you’ll find floating above the seafloor. Look for it in the middle of an underwater tunnel that leads toward the next barrel.
Nuclear Waste #6
The sixth barrel is also nearby, but you’ll need to descend more than 400 feet to reach it.
Nuclear Waste #7
The seventh barrel is deeper than 400 feet. Look for it resting on a ledge along the dark canyon wall.
Nuclear Waste #8
The eighth barrel is nearby, near the bottom of another deep canyon. Keep an eye on your depth as you descend.
Nuclear Waste #9
The ninth barrel is closer to the surface. Look for it at the base of a distinctive rock formation.
Nuclear Waste #10
The tenth barrel is nearby, resting at the bottom of a short underwater tunnel.
Underwater Briefcase #2 ($8,000)
The second underwater briefcase is close to the tenth barrel. Follow the coastline until you spot the rusted frame of a small sunken plane. The glowing briefcase is underneath the wreck, where it should be easy to spot.
Zone 3
Nuclear Waste #11
The eleventh barrel is a long way from the previous one. Use your map to navigate around any underwater obstacles until you reach the cove near the Humane Labs and Research facility. You’ll find the barrel on the seafloor, relatively close to the surface.
Nuclear Waste #12
The twelfth barrel is farther inside the same cove. Continue along the cove toward the shore, keeping an eye out for the barrel near the surface.
Nuclear Waste #13
The thirteenth barrel is also inside the cove, a little farther along and very close to shore. It’s almost at the surface.
Underwater Briefcase #3 ($10,000)
The third underwater briefcase is just outside the cove. Look for an old military truck teetering over an underwater cliff. The briefcase is inside the storage container on the back of the truck.
Zone 4
Underwater Briefcase #4 ($20,000)
The fourth underwater briefcase is quite far from the last one, but it has the second-highest payout. In the center of some small islands, you’ll see a cargo ship lying on its side. Swim to the top of the wreck and enter through the large hole caused by an explosion. You’ll find the briefcase among the exposed framework inside.
Nuclear Waste #14
The fourteenth barrel is at the entrance to another cove. It’s easy to find, but watch out for a nearby shark. You should be safe as long as you stay inside the submersible.
Underwater Briefcase #5 ($12,000)
The fifth underwater briefcase is inside the same cove. Look for the rusted wreck of a large steamer ship, then head to the large wheel on its eastern side. Like the first briefcase, this one isn’t visible, so swim around the seafloor inside the wheel until you collect it.
Nuclear Waste #15
The fifteenth barrel is just outside the cove, at the bottom of a deep trench about 450 feet below the surface.
Zone 5
Nuclear Waste #16
The sixteenth barrel is fairly close to the previous one. Like the last barrel, it’s at the bottom of a deep trench, so you’ll have to descend straight down to reach it.
Nuclear Waste #17
The seventeenth barrel is nearby, close to the surface and relatively easy to spot.
Nuclear Waste #18
The eighteenth barrel is the last one before you reach the industrial zone. Look for it resting on a small rock formation. It can be easy to miss if you approach from the wrong direction, so check around the rocks if you don’t see it right away.
Underwater Briefcase #6 ($16,500)
The sixth underwater briefcase is just west of the previous barrel. Look for a sunken airplane and search beneath its right wing for the briefcase.
Underwater Briefcase #7 ($7,500)
The seventh underwater briefcase is just north of the Port of Los Santos. Between two bridges, you’ll find a large sunken barge. The briefcase is on top of the barge, near some wooden beams.
Underwater Briefcase #8 ($11,000)
The eighth underwater briefcase is on the south side of the port. Look for a sunken cargo ship and enter the structure on its eastern side. The briefcase is on the seafloor, hidden among the seaweed.
Zone 6
Nuclear Waste #19
The nineteenth barrel is near the end of Del Perro Pier. You’ll need to navigate around the airport to reach it. Once you arrive, look for the barrel among the pier’s support stilts.
Nuclear Waste #20
The twentieth barrel is just north of the pier. It can be difficult to spot among the underwater plants, so look carefully around the seafloor.
Nuclear Waste #21
The twenty-first barrel is at the bottom of a small trench, resting on the edge of an underwater outcrop.
Nuclear Waste #22
The twenty-second barrel can be tricky to spot, as it’s tucked inside a small ring of plants and rocks on the seafloor.
Underwater Briefcase #9 ($25,000)
The ninth underwater briefcase is along the way to your next barrel, and it has the highest payout. You can find it on top of a sunken submarine, near the large open hatch.
Nuclear Waste #23
The twenty-third barrel can be difficult to spot. It’s hidden among the plants near a distinctive rock formation with three peaks.
Nuclear Waste #24
The twenty-fourth barrel is much easier to find. Look just offshore near Chumash Pier for the glowing yellow barrel.
Zone 7
Nuclear Waste #25
The twenty-fifth barrel is easy to miss. Look for it among the plants in a shallow channel just before you reach the Raton Canyon Bridge.
Nuclear Waste #26
The twenty-sixth barrel is near the military base. The water becomes murky in this area, making it harder to spot the barrel, so use the Trackify app to guide you.
Underwater Briefcase #10 ($9,000)
The tenth underwater briefcase is along the way to the next barrel. Veer slightly north until you spot a sunken tugboat. The briefcase is on the upper deck of the wheelhouse, on the walkway near the cabin.
Nuclear Waste #27
The twenty-seventh barrel is hidden in tall seaweed at the bottom of a short underwater cliff.
Nuclear Waste #28
The twenty-eighth barrel is hidden in another patch of tall seaweed just to the north.
Underwater Briefcase #11 ($12,500)
The eleventh and final underwater briefcase is along the way to the next nuclear waste barrel. Look for a sunken plane, then swim through its rear section to find the briefcase near the tail.
Nuclear Waste #29
The twenty-ninth barrel is at the bottom of a trench about 350 feet deep.
Nuclear Waste #30
The thirtieth and final barrel is at the bottom of another trench, nearly 500 feet deep. You’ll approach the submersible’s crush depth, so surface as soon as you’ve collected it.