Passage: The sea is named after the Russian explorers Dmitry Laptev and Khariton Laptev; formerly, it had been known under various names, the last being Nordenskiöld Sea (Russian: мо́ре Норденшёльда), after explorer Adolf Erik Nordenskiöld. The sea has a severe climate with temperatures below 0 °C (32 °F) over more than 9 months per year, low water salinity, scarcity of flora, fauna and human population, and low depths (mostly less than 50 meters). It is frozen most of the time, though generally clear in August and September.

Question: What did Adolf Erik Nordenskiold discover?
Nordenskiöld Sea