This mission can be hard if you're new at the game - the trick is to work quickly. The longer you stay in the passage, the more fortresses you'll encounter, and the lower your health will be for later.
Primary Objectives
- Reach the other side of the strait
- Sink the Hatsushimo
- USS Kane must survive
Secondary Objectives
- Destroy the seaplane hangar
- Destroy the PT boat base
Hidden Objectives
- Beat the level within 17 minutes
- Sink all cargo ships
Right off the bat, enter the repair screen and set all personnel to water repair. Your main threat for the mission will be the multitude of Gyoraiteis and their masses of torpedoes. Whenever you see a Gyoraitei, engage it with your machine guns. It may look like you're not causing a lot of damage to it, but your weapons are surprisingly effective against them. Use artillery if there's nothing else to shoot at, but especially if this is your first time playing, you may not be accurate enough to hit the Gyoraiteis. Don't stop for them though - they aren't your objective.
Two threats appear in short order as well - a fortress over on your left, and a Mavis coming in from the front. Your AA crew can handle the Mavis and, if you assigned your crew to water damage, its torpedoes can either be avoided or taken without much consequence. Most of the time though, the Mavis will be shot down before it can do anything.
The fortress, on the other hand, is a different matter entirely. Armed with a lot of cannons, it can put down a lot of feather and seriously hurt you. Fortunately, it doesn't move, so just lie your targeting cursor on top of it and open fire. Since it doesn't move, you don't have to lead it at all. Whatever you do, keep moving.
The fortress should blow up in short order. Continue on into the strait. Two sets of targets appear next - two cargo ships, or three LSTs. The LSTs aren't moving, but the cargo ships are - pull up to broadside with the cargo ships and lodge two torpedoes in their hulls to send them to the bottom. Once they're done, do battle with the LSTs, but don't worry if they don't go down - they're not mission critical targets, and they don't move - so if you want you can come back for them later.
Once you're past the cargo ships' carcasses, turn right towards the enemy submarine pen. In some other games, submarines are worth a lot of points - they aren't here, so focus instead on the fortress overlooking the next cargo ship area on the far right of the map. You should be sailing right towards one of the secondary objectives.
Cargo Ships and the Seaplane Hangar
The secret and hidden objectives are right next to each other, so go ahead and shell all the cargo ships and the seaplane hangar while you're at it. You should deal with the fortresses first though, since they are the major threat. The longer they're operational, the more shells they'll put down on you. Once they're done, shell all the cargo ships and the submarine pen at your leisure. Torpedoes work much quicker than cannons though, especially on the cargo ships.
At this point, you can either continue south then west to end up at the LSTs again, or you can do a three-point turn and head the way you came for the final secondary objective. If you opt for the former, look out for two fortresses near the other southern entrance of the strait - they can take pot-shots at you, but don't bother with them - keep moving. Give either torpedoes or cannonade to the LSTs if you wish, and continue on.
PT Boats and LSTs
Whether you did the three-point turn or went past the LSTs, you should be now either where the first set of cargo ships spawned, or a little south of there. Continue north towards the PT boat base, sheltered in a small inlet. Don't enter the inlet - you'll have a hard time getting out. Instead, simply plop yourself broadside with the base and shell it until the PT boat base is done. After that, head out of the strait to encounter the Hatsushimo.