&& (one_chance_in(5)
            || grid_distance(monster->pos(),
                             you.pos()) > 1
               // FIXME This is better expressed as a
               // function such as
               // monster_has_ranged_attack:
               && monster->type != MONS_ELECTRICAL_EEL
               && monster->type != MONS_LAVA_SNAKE
               && (monster->type != MONS_MERMAID
                   || you.species == SP_MERFOLK)
               // Don't submerge if we just unsubmerged for
               // the sake of shouting.
               && monster->seen_context != "bursts forth shouting"
               && !one_chance_in(20)
            || monster->hit_points <= monster->max_hit_points / 2
            || env.cgrid(monster->pos()) != EMPTY_CLOUD))

        && monster->wants_submerge())

}
bool monsters::wants_submerge() const
{
    // If we're in distress, we usually want to submerge.
    if (env.cgrid(pos()) != EMPTY_CLOUD
        || (hit_points < max_hit_points / 2
            && random2(max_hit_points + 1) >= hit_points))
        return (true);
    const bool has_ranged_attack =
        type == MONS_ELECTRICAL_EEL
        || type == MONS_LAVA_SNAKE
        || (type == MONS_MERMAID && you.species != SP_MERFOLK);
    const actor *tfoe = get_foe();
    int roll = 8;
    // Shallow water takes a little more effort to submerge in, so we're
    // less likely to bother.
    if (grd(pos()) == DNGN_SHALLOW_WATER)
        roll = roll * 7 / 5;
    if (foe && grid_distance(tfoe->pos(), pos()) > 1 && !has_ranged_attack)
        roll /= 2;
    // Don't submerge if we just unsubmerged to shout
    return (one_chance_in(roll) && seen_context != "bursts forth shouting");

    bool      wants_submerge() const;