Humans have sailed the oceans' surfaces for millennia (千年), but their depths remain effectively uncharted. Only about a quarter of the seafloor has been mapped at high resolution. Maps of most regions display only approximate depths and often miss entire underwater mountains or canyons (峡谷).

So a group of researchers has recruited some deep-diving experts: Elephant Seals and Weddell Seals. Scientists have been placing trackers on these blubbery marine mammals around Antarctica for years, gathering data on ocean temperature and salinity. For a new study, the researchers compared these dives' location and depth data with some of the less detailed seafloor maps. They spotted places where the seals dove deeper than should have been possible according to the maps-meaning the existing depth estimates were inaccurate.

In eastern Antarctica's Vincennes Bay, the diving seals helped the scientists find a large, hidden underwater canyon. An Australian research ship called the RSV Nuyina later measured the canyon's exact depth using sonar, and the researchers have proposed naming their find the Mirounga-Nuyina Canyon — honoring both the ship and the involved Elephant Seals, genus (动植物的属) Mirounga.

But seals can't map the entire ocean floor. The trackers used in the study could pinpoint a seal's geographical location only within about 1.5miles. Plus, because the seals don't always dive to the bottom of the ocean, they can reveal only where the bottom is deeper than in existing maps — not shallower. McMahon notes that scientists could improve on these data by using more precise GPS trackers and analyzing the seals' diving patterns to determine whether they have reached the seafloor or simply stopped descending.

The current seal-dive data can still be valuable for an important task, says Anna Wåhlin, an oceanographer. The deep ocean around Antarctica is warmer than the frigid waters at the surface, and seafloor canyons can allow that warmer water to flow to the ice along the continent's coast, Wåhlin explains. To predict how Antarctica's ice will melt, scientists will need to know where those canyons are and how deep they go.

Scientists are racing to study the volcano in Tonga that erupted just before sundown on January 15, 2022.

"Everything so far about this eruption is really strange," said Janine Krippner, a scientist with Smithsonian's Global Volcanism Program. "The sound of the explosion, the tsunami (海啸)waves that followed the eruption and the huge energy of this explosion, which equals to five to six million tons of TNT, are unlike any seen in recent decades. "

The sound of the latest eruption could be heard on distant shores around the world. According to Geoff Kilgour, a scientist from New Zealand, water likely has had a hand in it. "Perhaps the recent explosion had just the right mix of magma(岩浆) and water. Either more or less would have led to a quieter explosion," he said.

The tsunami waves that followed the eruption were even stranger. Tsunami waves usually start from the center of the eruption. Yet this time, waves appeared in other places, such as the Caribbean, far earlier than would be expected of a classic tsunami. In addition, as tsunami waves travel further, they usually become weaker. While the waves that hit the islands in Tonga were damaging, they weren't high enough to account for the surprisingly larger waves across the ocean.

Although many of the volcanoes in deep oceans usually aren't deadly, the recent event reminds us that how dangerous they can be and that how little we know about them.

However, monitoring underwater volcanoes is a complex task. GPS-which is frequently used to track changes in the surface as magma moves underground doesn't work on the seafloor. And obtaining real-time data from seismometers(地震检波器) on the ocean floor is expensive and technologically difficult.

The situation in Tonga has also shown how well the Tonga Geological Services (TGS) has dealt with the latest eruption. "They don't have a huge amount of money. They don't have a huge amount of staff," Janine Krippner added. "But they're asked to do a huge amount and they have done a really nice job to reduce the possible damages."

In Takoma Park, Maryland, in suburban Washington, people, adults or students, lined up at a pay phone outside a restaurant several times a week. 

"Once I put the phone out there, it just took off, " said David Schulman, a Takoma Park violinist who created the Bird Calls Phone. Listeners push 1 to hear a yellow-crowned night heron （夜鹭）， 7 to hear a pileated （红冠） woodpecker's call and 9 for the distinct scream of a red-tailed hawk. Instructions about how to use the phone are in three languages: English, Spanish and Amharic-a reflection of Takoma Park's Ethiopian community. In all, 10 birds native to the Takoma Park area are featured. 

In addition to being fun, listening to Bird songs can reduce stress and anxiety, studies show. Even hearing recordings of birds can relieve negative emotions. 

After noticing an abandoned, nonworking pay phone in town, Schulman wondered if he could turn it into something appealing. He said, "I really like the old technology of just picking up a receiver, pressing one button and having something happen. "Schulman thought bringing birds sounds to the abandoned phone was a way to add a bit of nature to the neighborhood. 

Takoma Park city officials agreed, and they budgeted $5, 000 to complete the project. Schulman reached out to The McCaulay Library in Ithaca, New York, which agreed to send him a few dozen recordings of native birds. He then managed to gain the help of software engineer and artist Branden Hall to rewire the phone to play different bird calls. Schulman said he persuaded several of his friends to record short descriptions of each bird to go with the calls. 

"One thing I like about the Bird Calls Phone is that it's the opposite of a loud broadcast, " Schulman said. "Only one person can listen at a time, and each person will take away their own unique experience. "