Heist Prep: Vault Explosives

"Do you know how hard it is to source some high-quality plastic explosives these days? 'Cause if we're taking on that vault door, we need the good stuff. The last batch from my usual supplier got picked up by some salvage crews working shipwrecks off the coast. The silver lining is: they leave their stash on the ocean floor overnight, I guess they figure no one is crazy or stupid enough to steal it. And that, my friends, is where you come in. I'm pinging you the GPS now."

- Lester's briefing.

Vault Explosives is a mandatory prep mission featured in Grand Theft Auto Online as part of the The Diamond Casino Heist update. It is a freeroam mission needed to progress The Diamond Casino Heist. Completing this setup give players explosives to open the vault door during the Aggressive Approach.

Overview
Lester informs the player that they can steal some explosives from some underwater wreckage where salvage crews keep their stash. This can be in places such as the Sonar Collections Dock in Paleto Cove or in Banning. However, when they get there, Merryweather agents are already stationed there, whom the player must avoid or they will become hostile.

The player must dive underwater to collect the two explosives, which are white boxes with orange lights, and bring them back to the Arcade. a scuba suit is provided nearby to help the player breathe underwater while searching for them. When both explosives are delivered, the mission is complete.

Lester Dialogue
"Okay, I guess we're not the only crazy or stupid ones in town, because if that's the job description, you can bet Merryweather's gonna apply. This doesn't change the plan though. Avoid them, shoot 'em, feed 'em to the sharks, I don't care. I've arranged for some scuba gear to be left nearby, I assume you don't plan on holding your breath."

- After collecting a thermal charge.