US military’s 340-pound solar-powered drone boat explained: How the Lightfish works and monitors border activity

The US has located unmanned boats in the Gulf of America to monitor maritime activity along its southern border. It was built by San Diego-based company Seasats. The Lightfish vessels use solar power and onboard sensors to watch the water without a crew. The boats have already supported surveillance on the Rio Grande, and the Pentagon is considering expanding their use.

On October 2, 2026, Seasats announced that a fleet of Lightfish vessels had been deployed from the Texas coast into the Gulf of America. The move expanded an existing surveillance program that began along the Rio Grande in January.

According to Reuters, the Pentagon is also considering adding as many as 50 boats to its current test group of 10 vessels.



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How does the solar-powered drone boat work?

The Lightfish is a small, self-driving boat that works without a crew. Its solar panels turn sunlight into electricity to run the boat’s motor and other equipment. Seasats says its Lightfish vessels can remain on station for up to six months, depending on the mission and operating conditions.

Each vessel is about 11 feet long and weighs approximately 340 pounds, according to the company's Gulf deployment announcement. Its small size allows two people to launch and recover it using a boat ramp or the back of a pickup truck. Seasats says the Lightfish can be configured with different equipment depending on the task.

Reuters reported that data from the vessels' sensors feeds into military software systems, including Palantir's Maven Smart System and Anduril's Fortress platform. The information can alert US Customs and Border Protection and Coast Guard units.

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The unmanned boats can therefore help identify activity for further investigation. Crewed units can then respond when necessary.

How long can the boats stay at sea?

Seasats says the Lightfish can remain on station for up to six months. This is one of the vessel's main advantages over conventional patrol boats and aircraft, which need fuel, maintenance and crew changes.

The boats are also designed to operate in rough sea conditions. Seasats says the Lightfish can operate in sea state 6 conditions, although actual performance depends on weather, equipment and mission requirements.

The company describes the vessels as solar-powered with a hybrid reserve system. This provides another source of power when needed. Each Lightfish costs about $240,000, according to Reuters.

What have the boats done on the Rio Grande?

Before the Gulf deployment, Lightfish vessels had been operating along the Rio Grande since January 2026 as part of Operation River Wall.

The Pentagon said the 10-boat test group had assisted with an average of 452 detections, 350 apprehensions and 100 turnbacks per month, Reuters reported.

In its October 2 announcement, Seasats said the fleet would support maritime border security by monitoring activity, including suspected drug trafficking and unauthorized vessel movements.

Unmanned boats can remain in a designated area for long periods without requiring a crew to stay aboard. They can also provide information to authorities who operate patrol boats and aircraft.