This Tutorial assumes you have in place in Radiant, a Skybox and Worldspawn settings.First create the Terrain Patches, I Used 6 512x512 with grids of 9x9 for each.

Now texture the patches with your chosen Texture, mine being duhoc_grass_yellow2Now bring up the Advanced Patch Editor ( Press key Y).Choose Paint Height, and using the sliders, in the 3d window, create your hollow in the terrain (press ALT key to perform this operation.

Now we need to create the blended mud for the bottom of the hollow.Select all your hollowed terrain and using the Spacebar, create a copy of the terrain.

Move it back into the same position as your Land Terrain.Now select a Texture for your mud. I used w_mud_blend.Using the Advanced Patch Editor, with Aplha Option chosen and Flatten Chosen, and ALT+Left Click to colour in the blend, ALT+Right Click to wipe out the blend, create your mud texture within the hollowed out part of your terrain. When finished it should look like this.

Now we need to add the Water.Create a Brush using the water_clip Texture, This brush needs to be as deep as the deepest part of your hollow and as wide/long as required to fill in your hollow at the top height where you wish your water level to be.

Now just select the top surface using CTRL+SHIFT+Left Click and texture the water surface with your chosen water texture, mine being water_rhine. I brought up the Surface inspector 'S' and fitted the texture to the area.

Now copy this Brush using Spacebar and reposition it, then Create a Terrain Patch from it with a Grid of 2x2, texture it with the same water texture 'water-rhine' and then invert the patch, move it 1 grid line lower than the top of your water brush and make it non-colliding. This will give an impression of surface water from underneath the water.

Now for the Triggers.Copy the Water brush again and reposition it to the same are as your water brush, Texture it with the Trigger Texture, then press in the 2d window, right click and choose Trigger - multiple.Now lets give this trigger a name. Press 'N' and enter the following:Key: targetnameValue: drownNow create another Trigger Multiple Brush the same size and place it 7 grid lines above your water level. DO NOT give this one a targetname!Now select the 1st trigger mulitple brush then the 2nd one and press 'W'. This connects the two brushes together.

Thats all that needs to be done in the map, expect for Global Intermission and Spawn Points. I added some grass in the hollow just for atmosphere.

Now Compile your map.Now for the scripting.Create a yourmapname_drown.gsc file and call it from yourmapname.gsc filethis is the scripting to go in this file.

// Multiplayer drown script for CoD
//
// written by [D]delica
// based on _noprone.gsc by r0ger and the stock IW S&D scripts ;)
// Modifed by Spikenaylor for COD2 using the tintscreen script from//[Nip] Drowning Water Script v1
//[Nip] by BionicNipple (bionic.nipple@gmail.com)
// To use this script, you'll need two trigger_multiples, set up pretty much the same
// way as r0gers' _noprone script. One should fill the area where you have water, so as
// long as the player is in the water they will be in contact with it. Open entity
// properties and give it the targetname 'drown'. Create another trigger_multiple above it,
// and connect it to the 'drown' trig as a target. (select 'drown' trig, then the target trig,
// and press W.) The base of this trigger should be at the same level as the surface of
// your water, or a little above, depending on how soon you want people to start drowning.
// This is all you need to do in radiant. Save, close and compile.
//
// In your yourmap.gsc, call _drown with "mapsmp_drown::main();" (no quotes ;) ), and make
// sure you place _drown.gsc in the maps/mp folder of your iwd. For compatibility's sake,
// please rename _drown.gsc if you use it (viz "mp_mymapname_drown.gsc", so ppl can customise
// it to their taste without creating problems with other mods/maps ;).
//
// N.B: the sounds and fx used in this script are all custom. If you want the same sounds,
// I suggest you rip them from Hamlet.pk3. Ditto the fx ^_^
//
// delicauk@gmail.com

main()
{ drownage = getentarray("drown","targetname");
if (isDefined("drownage"))
{
precacheShader("black");
precacheShader("white"); level.barsize = 288;
level.drowntime = 8;
level.hurttime = 6; for(d = 0; d < drownage.size; d++)
{
drownage[d] thread water();
}
}
}Water()
{
while (1)
{
self waittill("trigger", other); if(isPlayer(other) && other istouching(self))
other thread drown(self);
}
}
drown(trigger)
{
dceiling = getent(trigger.target,"targetname");
water_vision = undefined;
while (self istouching(trigger) && !self istouching(dceiling))
{
wait .125;
if(isDefined(self.drowning))
return;
self.drowning = true; if(!isDefined(water_vision))
{
water_vision = newClientHudElem(self);
water_vision.x = 0;
water_vision.y = 0;
water_vision setshader ("white", 640, 480);
water_vision.alignX = "left";
water_vision.alignY = "top";
water_vision.horzAlign = "fullscreen";
water_vision.vertAlign = "fullscreen";
water_vision.color = (.16, .38, .5);
water_vision.alpha = .75;
}
level.barincrement = (level.barsize / (20.0 * level.drowntime));
// level.player allowProne(false);
if(!isDefined(self.progressbackground))
{
self.progressbackground = newClientHudElem(self);
self.progressbackground.alignX = "center";
self.progressbackground.alignY = "middle";
self.progressbackground.x = 320;
self.progressbackground.y = 385;
self.progressbackground.alpha = 0.5;
}
self.progressbackground setShader("black", (level.barsize + 4), 14); if(!isDefined(self.progressbar))
{
self.progressbar = newClientHudElem(self);
self.progressbar.alignX = "left";
self.progressbar.alignY = "middle";
self.progressbar.x = (320 - (level.barsize / 2.0));
self.progressbar.y = 385;
}
self.progressbar setShader("white", 0, 8);
self.progressbar scaleOverTime(level.drowntime, level.barsize, 8); self.progresstime = 0;
d = 0;
f = 0; while(isalive(self) && self istouching(trigger) && !self istouching(dceiling) && (self.progresstime < level.drowntime))
{
d ++;
f ++;

wait 0.05;
self.progresstime += 0.05;
if(self.progresstime >= level.hurttime)
{
if(f >= 4)
{
radiusDamage(self.origin,9, 1, 1);
f = 0;
}
}
} if(isalive(self) && self istouching(trigger) && !self istouching(dceiling) && (self.progresstime >= level.drowntime))
{ self.progressbackground destroy();
self.progressbar destroy(); wait 0.025;
radiusDamage(self.origin,22, 3000, 3000); self.drowning = undefined;
self.sounder = undefined; randb = randomInt(4);
deathmethod1 = " made a hole in the water and lay down quietly to rest forever.";
deathmethod2 = " paid a long lasting visit to Davy Jones's Locker.";
deathmethod3 = " went diving without breathing apparatus.";
deathmethod4 = " swam like a brick.";

if (randb == 0)
iPrintLn( self.name, deathmethod1);
if (randb == 1)
iPrintLn( self.name, deathmethod2);
if (randb == 2)
iPrintLn( self.name, deathmethod3);
if (randb == 3)
iPrintLn( self.name, deathmethod4);
wait .05;
water_vision destroy();
}
else
{
water_vision.alpha = .5;
water_vision fadeOverTime(3);
water_vision.alpha = 0;
wait 0.05;
self.progressbackground destroy();
self.progressbar destroy();
self.drowning = undefined;
self.sounder = undefined;
}
wait .05;
}
}

This will now allow you in the water and still be able to shoot, but you can't clearly see and you only have a short time before you drown.

Enjoy, and hope this clear a few things up.

I have attached a zip file with the completed IWD file and the map file for your pleasure.
Spikenaylor.