Sometimes, when the player utilizes the Swingset Glitch with the Tudor swingset and a large truck like a Benson or Yankee, they may be thrown into Blue Hell for a few seconds and then back on the surface somewhere near the swing.
A trick some users do in multiplayer (in deathmatches and Free Mode) is fly a helicopter into the ground near the airport, and fly in Blue Hell, then come up in a hangar near where Annihilators spawn. Player can now shoot through the wall and kill other people, but they can't shoot the player. This is not advised, as it is cheating if it is in a death match.
Part of the south side of the Rotterdam Tower (just beneath the first high ledge) is non-solid, and can be entered with a helicopter to access Blue Hell. From here, the player can enter interiors they could not enter before, go underwater, and explore some buildings. The player may accidentally re-enter the "real world", however, as some "real" interiors are not visible from Blue Hell (this is especially true of tunnels), and entering these will restore the player to the normal game world. A video showing how to do this can be seen here
Upon entering the Schottler Medical Centre, turn right, and then right again. Player will be in a long hallway, with some windows and hospital privacy screen directly in front of the player. If the one throws a grenade near the wall, explosion will shatter the windows and move the screens. Player can now jump through the window and walk around in Blue Hell with some of the hospital's decals, doors, even pedestrians invisible for a while. However, if the one ventures too far towards the street, the surroundings will reappear. A video of this can be found here.
Driving east into the Booth Tunnel at high speed may put the player into Blue Hell for a few seconds.
Getting hit by a train underground while in a car may put the player into Blue Hell for a few seconds.
At Pier 45, facing the back from the water, the one needs to swim to the left, where are a bunch of wooden posts. Then the one needs to climb on to one. Niko will jump over it as if it was a fence and land in "water". If the one swims around, they will fall into Blue Hell.
Sometimes if the player is in a destroyed helicopter (i.e no rotors/tail) and then uses the health and weapons cheat to repair the helicopter, the player will fall into Blue Hell, and can explore it with the helicopter. The player can return to the game world by flying up through the ground.
Near the West River helipad, there is a cement wall partially covered in rocks. If the one swims against this in the correct spot (The rocks should be just below the waterline) for a few seconds, they will fall onto the seafloor. Now the one can walk through the cement wall into Blue Hell, although it is very easy to fall into the nearby Booth Tunnel and return to the real world.
Near Crockett Avenue and the big roller-coaster, there is a Go-Kart racing track. If the player crashes a helicopter with the nose to the ground on the south part of the track, they should sink into Blue Hell. If the player exits the helicopter, they will spawn on whichever street is nearest, or in the water.
At the second building by the Leapers Bridge between Albany Ave and Hematite St., the one needs to go to the front entrance of the building and then jump into the handrail where the mattress is. They will fall into Blue Hell for 5 seconds and end right back out into Hematite st.
In Middle Park West in Jade St., there's an alleyway, which if the one gets stuck in its entrance (at least with the FIB Buffalo), with a side up and the other on the floor, they need to get out, and if the one then tries to get in again they will fall into Blue Hell.
Sometimes, if player spawns a vehicle in the subway, it will seem to not be there, but if they press F/Y/Triangle, there is a high chance the car will be right under the subway line, causing the player to fall in the car into Blue Hell (tested in PC version).
In the dockyard near Francis International Airport, there is an entrance north of the big oil tanks in between the pipe lines and the ground (Only works in helicopter).
Player needs to go all the way south of the Star Junction. They will see a small place with few trees and benches. When the building is on the right, the one will see a space. If the player walks into the space they will fall in Blue Hell landing somewhere on the road.
There is a large fountain-statue, located near the hospital in Easton. Player needs to take an Annihilator (It is the easiest to do so), make a little distance to the statue, and ram its nose (the Annihilator) into the left side of the statue. They may have to redo it sometimes, and they may also have to use cheats. Tested on PlayStation 3.
When driving a car on the airport runway, sometimes when directly hit by the landing gear of a moving plane a player can be pushed through the ground into Blue Hell. After falling for several seconds the player will re-spawn on the runway surface. (PS3 tested)
The Lost and Damned
In the mission Buyer's Market, whilst getting to the ground floor, if the player aims an explosive correctly, he can launch himself out of the building into Blue Hell.
The Ballad of Gay Tony
In the mission Boulevard Baby, after the shootout in the Bahama Mamas club, Luis can fall through Blue Hell when walking up the stairs after the shootout, then re-spawn outside of the club.