MILDEN is Turkey's first indigenously designed submarine — the ~2,700-tonne Atılay class, in block construction at Gölcük since January 2025 with a methanol-reformer AIP and Turkish weapons. Delivery is promised for the early 2030s; nothing is yet in the water.
The submarine that "disappears" — Germany's Type 212/214 pioneered near-silent hydrogen fuel-cell propulsion, letting a non-nuclear boat stay submerged for weeks and slip past sonar so well it has "sunk" carriers in NATO war games. The world's benchmark export AIP submarine.
The conventional submarine that carries ballistic missiles — South Korea's KSS-III is a large, indigenous AIP boat with a vertical launch system for submarine-launched ballistic missiles, a strike capability almost unheard of outside nuclear-powered navies. Later boats add lithium-ion power.
Spain's AIP submarine — a large Navantia boat with a bioethanol fuel-cell air-independent power plant and a Tomahawk-class land-attack option. Famous as much for its troubles: an early design came out too heavy to surface, forcing a costly redesign before the first boat sailed in 2023.
Israel's Dolphin-class submarines — German-built diesel-electric attack boats with air-independent propulsion, a reported nuclear second-strike role, and a history wrapped in operational secrecy that only occasionally lifts.
China's primary conventional attack submarine with indigenous Stirling air-independent propulsion — a quiet, multi-week-endurance boat built for regional sea denial, and the platform behind Beijing's push into the submarine export market.
A Franco-Spanish diesel-electric attack submarine family with optional MESMA air-independent propulsion, exported to Chile, Malaysia, India, and Brazil, and the backbone of India's Kalvari and Brazil's Riachuelo classes.
Germany's pioneering fuel-cell AIP attack submarine — the ultra-quiet Type 212A, now evolving into the larger Type 212CD for North Atlantic/Arctic operations, operated by Germany, Italy and (on order) Norway.