"Every descent is heroic. It is the heroism of the people who go down to the deep," Chilingarov said. "We're doing it for science and, of course, for Russia's presence [at the North Pole]."
The immediate mission: to plant a specially made Russian flag directly beneath the North Pole.
At 12:08, Moscow time, the "Mir-1" submersible did just that, using a mechanical arm to plant the titanium flag on the bed of the Arctic Ocean.
A second Russian sub manned by an international crew reached the seabed about 30 minutes later.
Accompanying the mission was much talk that by planting the flag, the explorers were staking Russia's claim on a vast swathe of Arctic seabed believed to be rich in oil, natural gas, and mineral deposits.
Lindsay Parson, head of the Law of the Sea Group at the National Oceanography Center in Southampton, United Kingdom, says this is not the case.
"It's a tremendous scientific and logistical endeavor to do what those guys have done, and I take my hat off to them," Parson said. "But in terms of claiming the seabed and any sovereign rights in terms of any of its resources -- that is a completely separate and maritime legal process which is governed by the United Nations Convention on the Law of the Sea."
Under international law, Russia, Canada, Norway, the United States, and Denmark currently each control a 200-nautical-mile exclusive economic zone in the Arctic Ocean extending past their coastlines.
But the law also allows a country to file a claim on additional territory beyond its exclusive economic zone if it can define the outer limits of its continental shelf -- in this case the Lomonosov Ridge.
To make the claim that the ridge is an extension of Russian territory, Parson says, the country must develop a scientific case based on specific criteria within the terms of the Convention on the Law of the Sea.
In 2001, Russia filed a claim to the commission that examines such cases, but wasn't able to supply enough information to support it.
Speaking to journalists in Manila ahead of today's dive, Russian Foreign Minister Sergei Lavrov indicated that buttressing the country's claim was the ultimate purpose of the expedition.
"The goal of this expedition is not to plant a border post and assert Russia's rights, but to prove that our shelf stretches to the North Pole," Lavrov said. "There are concrete scientific methods for that. And I think this expedition, including the minisubmarine reaching the bottom of the Arctic Sea in the area of the North Pole, will supply additional scientific evidence for our aspiration."
Russia is not the only country with claims to the territory in question -- Canada has long claimed historical rights to the icy lands and waters.
Canadian Foreign Minister Peter MacKay, speaking to journalists today, said "there is no threat to Canadian sovereignty in the Arctic."
"You can't going around the world these days dropping a flag somewhere," he said. "This isn't the 14th or 15th century. So, this is really not a question."
If there were a dispute, he said, the Law of the Sea would kick in. And he made clear that "there is no dispute. This is Canadian territory, plain and simple."
But for today, at least, there can be no denying Russia its victory in being the first to reach its depths.