Beneath the Arctic Ocean an orchestra of natural and human-made sounds plays—from cracking sea ice and whistling beluga whales to humming ship engines. MIT Lincoln Laboratory researchers first captured this cacophony using commercial off‑the‑shelf sensors during the U.S. Navy’s Operation Ice Camp (OIC) in 2024. In March 2026 they returned with a higher‑fidelity geophone that detects vibrations in sea ice.\ \ “We’re interested in sounds under the ice,” says Ben Evans of the Advanced Undersea Systems and Technology Group. “Our 2024 data contained marine‑mammal songs. We need to understand how these signals propagate through ice and how to separate them from other sources.” As Arctic ice rapidly fractures and melts, new maritime routes open, affecting military and commercial activities. Identifying the acoustic signatures of ice cracking will help predict coastal resilience, shape geopolitical strategy, and monitor adversary actions.\ \ Since 2022 the team has been attending OIC, aiming to deploy a network of low‑cost sensors for continuous monitoring. OIC, held every two years for three weeks, provides a temporary drifting‑ice runway and insulated tents that let researchers test prototypes in an otherwise inhospitable environment. The 2026 mission faced back‑to‑back blizzards, temperatures of –25 °F, and winds up to 30 mph, grounding all flights. The original plan of two ice trips—deployment and retrieval—was forced to change by the weather.\ \ During the downtime, David Whelihan prepared a through‑ice communications modem from Norwegian startup Havguard. The device uses magnetic fields instead of radio‑frequency signals, which attenuate quickly in seawater. Harsh conditions in Prudhoe Bay caused system failures, prompting Whelihan to return to the lab for repairs.\ \ The team arrived at the camp on March 7 and experienced five days with no flights, whereas a typical OIC day sees six to nine. The next day they loaded sensors onto a sled and were towed out by a 4×4 tracked vehicle driven by an Arctic‑survival expert. After deploying about a quarter of the planned sensors, they were ordered back because the blowing snow would soon erase their tracks. A week later, clear weather allowed them to retrieve the sensors and leave.\ \ Whelihan then brought the repaired modem back to Prudhoe Bay, only to be hit by another blizzard. The lab partnered with UIC Science, a business unit of the Ukpeaġvik Iñupiat Corp., to conduct the modem test on land‑fast ice near Utqiaġvik, Alaska. Riding snowmobiles, the researchers drilled a 2 × 3 ft hole through 3.6 ft of ice and lowered a remotely operated vehicle (ROV) carrying the Havguard modem. The modem consists of a magneto‑inductive transmitter (below the ice) and receiver (on the ice surface), each housed in polycarbonate domes for protection.\ \ Prior to the Arctic test, the team trialed the modem on a large freshwater reservoir in Vermont, which, while not representative of salty sea ice, allowed them to refine procedures. During the Arctic experiment the ROV was equipped with a Doppler velocity logger and a four‑beam sonar to record its speed and heading. Drone imagery was overlaid on the site map to track the ROV and calculate data‑transfer rates. The alpha prototype achieved roughly 1.2 KB/s of through‑ice communication, a promising result that justifies further development. Future versions may relay data out of the Arctic via drones or satellites.\ \ While in Utqiaġvik the team joined the Piuraaġiaqta spring festival, watched a harpoon‑throwing contest, and supervised a kids’ snowmobile race. They also visited a local middle school, where they taught eighth‑graders sonar concepts through a game. “Connecting with the Arctic community is an important aspect of our work,” Evans notes. At OIC 2024 they met a University of Maryland professor specializing in cryoseismology and now plan to apply machine learning to distinguish icequakes from marine‑mammal vocalizations.\ \ Looking ahead to OIC 2028, the researchers will design air‑droppable sensor versions and continue collaborating with Havguard to optimize the modem’s packaging for easier Arctic deployment and integration with their sensor suite. “The through‑line in all this work is minimizing boots on the ice,” says Whelihan. “Weather controls our access, so we need ways to get sensors where we want them and retrieve data even in extreme conditions.”\ \ The project is funded by the laboratory’s internally administered R&D portfolio for mission‑critical technology and its Advanced Concept Committee, which supports high‑risk, high‑reward early‑stage research addressing critical national‑security gaps.\ \ Review