A video guide for this exploration can be found at entry #5 in Episode 1 of Five Minute Explorations, which is shown above.
Just off the coast of Gilneas, there is an abandoned submarine called the X-2 Pincer…
Part of a Horde quest during the Battle of Gilneas, the X-2 Pincer exists only to be viewed through a spyglass during a single cutscene. However, Alliance and Horde players alike can find it in the bay outside Gilneas, floating abandoned and unmanned with it’s lights and machinery still running, a forgotten ghost ship in the harbor.
While not accessible by either faction via normal means, explorers can use the method detailed in the video above to gain access to the forgotten inner chambers of the sub themselves. And doing so reveals just how oddly intricate the level of detail and decoration is, even in areas that would never normally be visible to players.
Entering the lowest level of the X-2 Pincer, you’ll find yourself in an abandoned but elaborately decorated area without water physics of any kind; which is significant because it means that at some point during the models creation the developers put in the effort to differentiate the ship from the surrounding ocean.
The lowest level sports three large windows which grant an expansive view of the surrounding bay, a command console with a steering wheel and two captains chairs, and a large spiraling walkway that wraps around the front of a multi-level broiler connected to a network of pipes (assumedly what powers the submarine). The subs entire interior is astoundingly detailed, even including rivets on the walls and buckets by the broiler hatch.
Traveling up the spiral ramp to the second story of the Pincer leads us into a room that appears to be flooded with water. However moving our camera causes the water to randomly flicker on and off of the screen. This is because the surface of the ocean is intersecting with the sub, and can only be seen inside the vehicle at certain angles.
Continued exploration reveals that the second floor of the X-2 Pincer is as intricately decorated as the first, further supporting the theory that at one point it was planned for players to be able to access the inside of the sub.
However, for whatever reason any such accessibility was scrapped, and all that was left behind is a ghost ship floating unmanned and forgotten in Gilneas Harbor.