gl_turbalpha
This variable determines the level of opacity for liquids, which requires the use of maps that were VISed with transparent water. When using maps that have not been VISed in such a way, you have to use "r_novis 1". If "r_novis" is set to "1" or when using a map VISed with transparent water and using setting "gl_turbalpha" to a value lower than "1", the player will be able to see objects and walls through liquids if the server allows that. This is a very nice feature to have in the game, for more information refer to the "r_novis" command. You can use any value between "0" and "1" for "gl_turbalpha", here are some Examples:
0.00
Transparent.
0.25
Low opacity.
0.50
Medium opacity.
0.75
High opacity.
1.00
Solid.