I'm back to MW and I want to make a new version of Better Music System. At this moment I want to add a new feature, underwater music (among others). As for exterior cells, it seems for what I could see that it is enough to check the z coordinate of the player to control if he/she is underwater, but I need more testing tobe sure.

What I need now is a mod that includes interiors acting as exteriors, since I don't know if the same method works for them as well. Could someone tell me what mod to download?

Princess Stomper's Mournhold Expanded springs to mind, but it is quite a large download...

Not sure if it is possible, but if basing the music off of the 'z' coordinate doesn't pan out, would writing a script checking for the use of the swim animation be possible?

http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=1779 by Dale Stocker & Fernelf has some submerged interiors that you could use for testing.
It is not so easy to test for player underwater in interiors, as there is not a "GetInteriorBehavingAsixterior" like function, a possible detection method in interiors is testing for player swimming sounds. Here is a (untested) example script

begin ab01underWaterCheckScript; interior water check based on Zappara's temperature mod script; player must be moving / not levitating to emit splash soundsshort goodWatershort pcUnderWaterfloat z1if ( GetInterior )	if ( player->GetSoundPlaying "FootWaterRight" )		set goodWater to 1	elseif ( player->GetSoundPlaying "FootWaterLeft" )		set goodWater to 1	else		set goodWater to 0	endifelse	set goodWater to 1endifif ( goodWater )	set z1 to ( player->GetPos Z )	set z1 to ( z1 - GetWaterLevel )	if ( z1 < -64 )  ; this is just an example, probably it would be better change -64 to something good for all races		set pcUnderWater to 1	else		set pcUnderWater to 0	endifendiffloat delayif ( delay > 0 )	set delay to ( delay - GetSecondsPassed )	returnendifif ( pcUnderWater )	MessageBox "player under water detected"	set delay to 4endif end

Very interesting abot, however it seems that with that method the player must keep swimming to emit sounds, but if he/she stops? Although, yes, indeed this can be used with some adjustment. What I've done is much simpler 'cause it seems that every object/static in game with negative z coordinate is underwater, it did sound strange to me at first but maybe it's just how the world's been built. And I wanted to not make underwater music trigger if you just wanted to pass through a river without plunging.

EDIT: another thing, I'm not going to make u/w music for interiors, I'll leave tombs/caves/etc music as they are now, even if there is water in them.