Semisubmersibles

Milestones for Semi-Submersible Boats in Late 2025: Completions, Orders and Operations

December 2025 witnessed significant advances in semi-submersible vessels, with Sembcorp Marine unveiling the world's largest semi-submersible passenger vessel Sleipnir and alligator, U.S. strikes against suspected drug trafficker semis, China unveiling their mysterious trimaran, and JSI Alliance's inaugural cargo operation taking place during this month. Allseas advanced their Grand Tour HTV project with orders and designs.

European Union

Drug Enforcement Agencies Seize Narco-Sub Semi-Submersible in North Atlantic Amid Increased Maritime Interdictions

A drug-smuggling semi-submersible the size of a school bus was caught in the North Atlantic in late November 2025. Another similar self-propelled semi-submersible was intercepted 1,000 nautical miles off Lisbon by Portuguese forces in a European Union-funded operation. Both operations highlighted the nadir near the end of 2025 for narco-submarines operating internationally.