Going deeper into the cave can be both dangerous and difficult. To move further one needs to plunge deep into the darkness of the poisonous waters. The struggle does not end here, the further you move down, the lesser the amount of O2. And at a place already full of poisonous gases, lack of oxygen is the last thing you can dream of.
The human body can only survive for a couple of hours in these Romanian depths. The question that might strike your mind now is; Why go beyond your limits to explore a smelly, creepy cave?
The answer: The deeper we move inside, the greater the number of life forms and creatures that have adapted to these depths.