‘Tis the season of disappearing islands. Late last month, a remote Hawaiian island, once an important nesting site for green sea turtles, was all but wiped out when Hurricane Walaka tore through the Pacific. Now, as Justin McCurry reports for the Guardian, an uninhabited islet off the northeastern coast of Japan has vanished, its absence for some time unnoticed by residents of a nearby village on the main island of Hokkaido.

Hiroshi Shimizu, an author who has written about Japan’s islands, was first to remark on the disappearance of Esanbe Hanakita Kojima. During a visit to Sarufutsu, a village on the northern tip of Hokkaido, he realized that the island was nowhere to be seen, and reached out to the local fishery cooperative association, according to the Asahi Shimbun. The association consulted its sea chart and confirmed that where Esanbe Hanakita Kojima once stood, there is now only empty sea.

The island was last surveyed in 1987, at which point it protruded less than five feet above the water. The Japan Coast Guard has theorized that the little island was likely eroded by wind and ice floes that form in the Sea of Okhotsk, which lies between Siberia and Russia’s Kamchatka Peninsula.

“It is not impossible that tiny islands get weathered by the elements,” an unnamed coastguard official tells the Agence France-Presse.

But authorities had little other information to offer—they could not even say how big the island was before it vanished, according to the AFP. Japan only named Esanbe, along with 158 other uninhabited islands, in 2014, as part of an effort to cement the parameters of its territory.

Under international law, nations can only lay claim to areas around islands that are visible at high tide, and the disappearance of Esanbe “may affect Japan's territorial waters a tiny bit,” the coastguard official tells the AFP. But though any potential loss will be small, the coastguard plans to carry out a “detailed survey” of the waters that engulfed the missing island, reports the Japanese outlet NHK.

The area where Esanbe once peeped out from beneath the water is contentious, lying west of the four Kuril islands (known in Japan as the Northern Territories), which have been a sore point in relations between Japan and Russia for decades. Russia took control of the Kurils from Japan at the end of WWII, but both nations have laid claim to the resource-rich islands, which are coveted for their fishing grounds and deposits of rhenium. Long-standing disputes over the islands have stopped Japan and Russia from signing a formal peace treaty to end the war. Russian President Vladimir Putin said in September that he would like to sign a deal this year, but it seems unlikely that negotiations will move forward while the tussle over the islands remains unresolved.

“[O]ur position that the Northern Territories issue should be resolved before any peace treaty remains unchanged,” said Yoshihide Suga, Japan’s Chief Cabinet Secretary, according to Al Jazeera.

The loss of Esanbe may slightly shrink Japan’s claims to an area where it would like to secure its presence. But on the bright side for the country, landmasses have been known to not only disappear, but also materialize in the region, as the AFP points out. In 2013, for instance, a landside caused a nearly 1000-foot strip of submerged coastline on Hokkaido to rise out of the sea, making Japan just a little bit bigger.