The Death Tunnel (also known as the Tunnel of Death) is one of the most dangerous locations in Hungry Shark Evolution. It is the longest Underwater Current in the map, and travels from the West to East.
It can be survived with fairly low end sharks like tiger sharks or even hammerhead sharks. Anything above great white will not find it a challenge to survive in the tunnel, except for the possible lack of food. A sunken treasure item can be found here, which are the False Teeth, which are very easy to miss (astonishingly, even with the treasure map!), causing one to possibly have to turn back, if one is looking for them.
However, returning may be hard for smaller sharks as there is an underwater current in the Death Tunnel (direction: west to east). Mr. Snappy and Big Daddy have to get a mission shell in the Death Tunnel. At any rate it is a good idea to have a sturdy health bar before entering, as smaller sharks may die to the magma jets, mines and pink jellyfish and larger sharks may run out of food.
The Death Tunnel can be found on the right side of the entrance to the cave which hosts the Moon on a Stick treasure item. There is another entrance into the Death Tunnel in the ocean where the Tiger Shark's drop point is. But for it, you'll have to reverse the current.
The Tunnel of Death is, true to its name, is full of hazardous objects like Mega Mines, Death Mines, Pyro Sharks, and Volcanic Jets. Small sharks have no chance of surviving here. The underwater current will push you into Mines and Volcanic Jets. Pink Jellyfish who also appear around the entrances of the tunnel are another danger. Interestingly enough, the Lava Baby protects you from Mega Mines, Death Mines, Pyro Sharks, and Volcanic Jets. With the Lava Baby equipped, the Reef Shark could probably cross the Death Tunnel if not for the Pressure Damage.