The SHINKAI 2000 from JAMSTEC was the first manned submersible from Japan, it was capable of operating at a maximum depth of 2000 meters.
SHINKAI 2000 Papercraft (Submersible) [Download]
SHINKAI 6500 Papercraft (Submersible)
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Ancient Submarine Papercraft
Ponyo Papercraft - Fujimoto's Boat (Submarine)