The beasts all charged into the water violently. As soon as they had arrived, stealth was already thrown out of the window. The enemy would notice them anyway since they were land beasts and couldn't simply act like sea beasts. Therefore, there was no sense in trying to sneak in.
Every human would think that such a frontal assault would be reckless and stupid, but that was only true for human standards. Beasts didn't have things like Formation Arrays and walls. All they had was some advantageous natural terrain and their bodies. All in all, it didn't make much difference to beasts if they were the ones attacking or defending.
Gravis was in the middle of the group while the level five Lords were at the front. The first thing they would do is find their opponents and fight, while Gravis would take out one level five Lord after the next.