How do you do the runescape swimming glitch?

Question

How do you do the runescape swimming glitch?

Answer 1

You could swim

Answer 2

You can't anymore.

What you used to do was fall down the trapdoor in someones throne room and fall into the pit with the monster with tentacles. As you fall down, you teleport to any place and you should be swimming in the ground. It doesnt work anymore though!