Adrenum raises $18M Series A to build scalable sonar hardware for undersea domain awareness

Adrenum raises $18M Series A for undersea sonar sensing

Adrenum builds passive sonar hardware and software to track submarines, unmanned underwater vehicles, and semisubmersibles — a domain that, by Matt Cernosek's account, is increasingly contested and chronically under-monitored. Surface vessels are well covered by cameras and radar; everything below the waterline is not.

The company's two core products are Pearl, a passive sonar buoy, and Obsidian, a command-and-control platform that ingests sonar data, runs machine learning against it, and puts tracked contacts on a map for operators. Cernosek says the system delivers processed output in under three seconds of latency and has gone through three hardware generations since Adrenum's last public appearance.

“We raised $18,000,000. Adrenum builds scalable sensing infrastructure for undersea domain awareness — finding submarines, unmanned underwater vehicles, semisubmersibles. We've gone through three generations of hardware and just completed a three-and-a-half week deployment with UUV Group in Keyport, Washington with no mission-ending failures.”

Field deployments

Adrenum recently completed a three-and-a-half-week deployment with UUV Group in Keyport, Washington — the unit that governs how unmanned underwater vehicles operate — with no mission-ending failures. Earlier this year the company participated in a large fleet exercise in San Diego. The pitch to operators is deliberately low-friction: Pearl is small enough to kick off the side of a boat rather than requiring a barge and a week of pre-deployment preparation. Cernosek says end users have been asked to break the hardware and report back, and the feedback loop is feeding directly into iteration.

The data moat

Sonar is harder to train than radar because the ocean's environmental variables don't transfer between locations the way air does with RF signals. There's no equivalent of a Scale AI dataset for classified undersea signatures — Cernosek says operators have to build the repository themselves through actual deployments. That's an explicit strategic bet: by owning the hardware, Adrenum accumulates a proprietary library of sonar signatures that third parties can't easily replicate. Off-the-shelf data does contribute at the margins — whale calls and other ambient ocean noise help the model distinguish biologics from potential threats — but the defensible data comes from fielded hardware.

Platform positioning

Cernosek is clear-eyed about where Adrenum sits relative to larger defense platforms. Anduril and Palantir run higher-level command-and-control systems, and Adrenum eventually wants to pipe its data upward into those. For now, owning the undersea sensing layer is the priority. Sonar data is highly classified and compartmentalized, which makes integration complex, but Cernosek frames the hardware-first approach as the only credible path to controlling that data rather than ceding it to third-party integrators.

The $18M Series A positions Adrenum to continue scaling both hardware production and its sonar signature repository ahead of what Cernosek describes as forthcoming announcements.