Jump Location Var: E045E4.
Set to 02 and you'll have menu access while submerged in the sub. I needed to find this so I can fix the bug that causes Emerald Weapon battle music when resurfacing. [although I already had it in Ochu. Whoops! ]
Event loader: 76420A
Events are loaded from here. There are certain types. Special events, like Emerald Weapon's movement and battle are initiated from 7642D1. For example, when your sub comes into contact with Emerald, certain new functions are called from the parameter placed into the function (0x300 is deducted inside the function, so below are actual jump IDs):
This chain is in order:
4A, 7659DF (sonic boom effect)
07, 7650d2
1D, 7657C4 Electric sound effect
36, 7650E7 Sub pushed away
28, 765184
3B, 7655F1
34, 765BF2
48, 7655CC Battle swirl - battle intro
55, 765808
17, 7657E1 Initiates Emerald Weapon battle
The World Map simply has opcodes like Field, it seems. So you could call for a sonic boom effect around a model at any time.
03 is Emerald Weapon movement
04 is involved in Emerald Weapon's movement. May be the direction change operations (the movement path).
05 Emerald Weapon collision detection. If this isn't called, the sub will not interact with Weapon - but the battle can still happen if you touch a certain part of Weapon. Issues will arise. Seems to also depend... I can't always make the collision disable. May be the return value I am messing up.
06 is Emerald Weapon movement.
21 Unknown
It is likely that Ultima Weapon shares some or all of these functions.
edit.
[00E39BC0] is used for the collision and movement. When it's set to 1, there is no movement and all collision is off. It's used by 05.