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.
Taiwan's home-built deterrent — the Hai Kun ("Narwhal") is the island's first indigenous submarine, built with quiet foreign help to give Taipei a stealthy weapon that could threaten any Chinese invasion fleet. After decades unable to buy submarines abroad, Taiwan built its own.
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.
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.
Russia's troubled Project 677 diesel-electric attack submarine — a mono-hull design intended to replace the Improved Kilo with Kalibr capability and planned air-independent propulsion, but plagued by decades of delays and an absent AIP system.
Russia's diesel-electric Kalibr-capable attack submarine — the "Black Hole" of the Black Sea, a widely exported SSK and the platform behind the only documented submarine-launched cruise-missile strikes in combat.
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.