I hate to come across all worldy wise and much travelled, but I saw The Deep on my visits to Japan a year and a half back. Since then it's failed to materialise in Britain's arcades. That hasn't stopped US Gold from licensing it, and I for one am glad.
Back in the land of the rising sushi, The Deep was a scrolling shoot-'em-up of the old-fashioned depth-charge-the-subs kind. A destroyer cruises left-to-right across the screen destroying any underwater craft that float beneath it, until it confronts a mega boat of the end-of-level variety.
By sinking various underwater craft pods are released which float to the surface and can be collected. A helicopter appears and drops a yellow object that will give you extra firepower, and most importantly a mini craft which allows you to descend to the bottom of the screen and pick up a glowing pod. This triggers the scrolling and the screen begins to move, taking you onto another section. All the time though, you're beset by subs which release mines, leaping manta rays, and rocket firing jellyfish.
Making your way across the screen brings you first to a confrontation with a large cruiser which will ram you if you don't sink it first, then to a huge underwater sub which fires humungous polaris missiles from various silos dotted around its superstructure. Sinking this takes you onto a Missile Command type section in which you have to destroy torpedoes as they're launched at a cute little flotilla of ships. After that it's onto the next level.
The Deep is entertaining stuff. The action is a little slow at times because of the way they've interrupted the scrolling, but it's varied, and it does get quite hard on later levels. The graphics are extremely pretty, with well drawn, colourful seabeds and nicely animated marine life. Sound is limited to a few sonar pings but I guess a jolly tune might destroy the atmosphere.