Herbert sighs, and is ready to walk forward into the water when....Lapis fully just disappears. Only the shape of the water creature remains. He's apparently too late, in some way that honestly makes zero sense to him but he's done. It's very clear to him that he's not the person who should be handling this. He's a doctor and a scientist and there is no corpse left to reanimate and the people on the radio were wrong.

His best move now is to back away from the pond and out of the scenario, his sword dissolving as he does so. If he finds someone already searching he can guide them back, and they can do something.