Paulus, you need to change the starting depth of your sub in the mission files.
Open "Sh3MissionEditor" from the root folder of your Silent Hunter install. Use the editor to open the mission file you want to play, in SH3\data\SingleMissions\English\[Mission Name]\[Mission Name].mis. The mission map should pop up.
In the white panel on the right side of the screen, under the "Explorer" tab, there is a list of units. Find your sub's name, right-click, and go to properties. You'll know you're editing the right unit if the "Human Control" box is checked. Next to that box is "Height (M)". This is your starting depth. Set it to zero.
You'll have to do this for each mission you want to play as a surface ship. Then you might get sidetracked editing all the OTHER things about the mission you never knew you could change.
