The Baltic harbour porpoise is critically endangered, with only a few hundred animals remaining. One threat is ghost nets — fishing nets that have been lost or dumped at sea. Porpoises risk getting entangled in these rogue nets and drowning when they cannot reach the surface to breathe. WWF is working to retrieve as many ghost nets as possible from the Baltic Sea, but locating these nets is like looking for a needle in a haystack. Now, WWF is testing new technologies to make finding the nets more efficient.