How deep is the deepest ocean—and how precisely can we actually measure it? A Japanese research team has mapped the Challenger Deep in the Mariana Trench using the EM124 multibeam echosounder aboard the research vessel Hakuho-maru.

It’s no secret that plastic and other human trash are a problem for marine life, but our understanding has long focused on the ocean’s surface. Now, a more complete picture is coming into focus, revealing that even some of our planet’s greatest depths have become home to our debris. As described in a study published on September 16, 2026 in the open access journal PLOS One, an international team led by Dr. Daniel Lauretta of Argentina’s natural science museum surveyed the Mar Del Plata Submarine Canyon in the southwestern Atlantic, finding that our trash has accumulated in a part of the planet we typically consider pristine.

Reducing excessive boundary-layer mixing helps ocean models recover internal lee waves

Underwater gliders can cruise for months and cover thousands of kilometres, but one glider can sample only a small slice of the ocean. A review in Ocean maps how researchers have turned these platforms into coordinated fleets for observing ocean phenomena and detecting underwater targets. It also charts the control, communication, and planning methods that could make such fleets self-healing and energy-aware.

The longest satellite record ever assembled shows that Greenland and Antarctica have lost 11.3 trillion tonnes of ice since the 1970s, raising global sea levels by more than 3 centimetres – and that most of the loss has come from glaciers flowing faster into the ocean, not from melting at the surface.