This creates a movement sort of like a floating lantern. But it needs a lot of work before I will consider it even close to done.

// V2 //
 
float limit = 10.0; // This is the radius that the object is allowed to drift up to.
// 20.0 == a 40 meter circle.
 
float offset = 0.0; // Use this float to offset the height of the object in relation to the water surface.
// The object will (when the offset is zero) float with its geometric center at the level of the water surface.
 
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
float float_height;
 
vector home;
 
FloatAbout(vector pos)
{
    llSetTimerEvent(limit);
    @a;
    float num_x = (llFrand(limit / 2) - (limit / 4));
    float num_y = (llFrand(limit / 2) - (limit / 4));
    vector target = <(pos.x + num_x), (pos.y + num_y), float_height>;
    if(llVecDist(target, home) <= limit)
    llMoveToTarget(target, (limit * 1.5));
    else jump a;
}
 
default
{
    on_rez(integer param)
    {
        llResetScript();
    }
    state_entry()
    {
        float_height = (llWater(ZERO_VECTOR) + offset);
        llSetStatus(STATUS_ROTATE_X | STATUS_ROTATE_Y, FALSE);
        llSetStatus(STATUS_PHYSICS | STATUS_PHANTOM, TRUE);
        home = llGetPos();
        llSetTimerEvent(0.1);
    }
    timer()
    {
        FloatAbout(llGetPos());
    }
    touch_end(integer nd)
    {
        if(llDetectedKey(0) == llGetOwner())
        FloatAbout((home = llGetPos()));
    }
}