While dropping a pistol from the gear menu, then exiting quickly, the character goes into a swimming animation while out of water.
- Legacy ID
Enter the gear menu, drop your vest and your rifle, then exit the gear menu. Go back into the gear menu, drop your pistol then hit escape and it should put you into a swimming animation.
While using a diver, enter the gear menu, drop your primary rifle, then exit the gear menu, go back into the gear menu, drop your pistol, then exit the gear menu, and you should see the swimming animation.
Please check out this video on YouTube to see exactly what happened. (The methods above were not used in the video)