Their mobile phone signal identified their last known spot as Tarutao Island in Satun province, Phuket’s deputy police chief Pol Colonel Witoon Kongsudjai said on Tuesday.
“We are going to track them down,” he said.
The suspects have been identified as Chad Andrew Elwartowski, an American bitcoin investor, and his Thai girlfriend, Supranee Thepdet (aka Nadia Summergirl).
Authorities have accused them of several laws violation, including taking action that diminish Thailand's sovereignty.
Seasteading is the concept of creating permanent dwellings at sea, outside the territory claimed by any government.
The authorities have already removed their floating home from the sea and kept it as evidence.
Police say they have prepared sufficient evidence ready and arrest warrants for the couple should be issued soon.
At this point, police are waiting for the Office of the Attorney-General to appoint its officials to join the investigation into this case.
The office's representatives are necessary because the alleged crime took place outside Thailand's territory.