I enjoy building these little HobbyBoss sub kits from time to time as a break from more complex projects. They're good little kits.
This is the USS Greeneville carrying the Advance SEAL Delivery System mini-sub prototype. The ASDS project has now basically been abandoned, after the single prototype suffered a fire.
The Greeneville is probably best known for being involved in two collisions and a grounding in the space of one very unlucky 11-month period in 2001-2002.