According to International Law, what process governs claims to new, previously undiscovered land?

In a recent news article, a fishing vessel somewhere in the South Pacific came upon a new volcanic island. Considering that at the time of discovery, the smoke from the eruption had not yet settled, this was truly new territory and the crewmembers of the vessel were the first to discover this land. This was quite a substantial find as the island was over a mile across. uming that the island was in international waters, what, if any, claims do the crew of the fishing vessel have for this land, and who’s jurisdiction would any such claims fall under?