The first thing this stage shows us is that we're going to have water to deal with. Interestingly, the water is shallow enough that it hardly affects Mega Man's movement, and instead only serves as something for one of the new enemies to interact with.
SRU-21/P drops from the ceiling and hovers in the water for a while, after which it explodes to send three projectiles upward. At this point, all the player has to worry about is stopping before it lands on Mega Man's head.
The real star of the show is Pelicanu, a robot pelican that drops robot fish which flop around for a while on the floor. Sadly, they missed an opportunity to have the fish swim around in the water, as they disappear on contact instead. The Pelicanus are great at messing with expectations though, as the first can be walked under but is low enough to encourages an attempt to slide, which the fish will prevent.
The second one flies higher, but the fish drops just close enough to hit a player trying to walk normally. So far the SRUs haven't done much, but their projectiles will be more dangerous on the small blocks, which rewards players for shooting them on the way down. Also, while the Pelicanu here can pass overhead safely, the shots from SRU and the fish will be a severe problem if one or the other isn't destroyed.
The next two Pelicanus are nothing new, but the rightmost SRU in the second image is in a good spot to catch a player trying to deal with them carefully. The final SRU is really only there to waste the player's time.
Gabgyo returns for a full underwater segment, this time swimming back and forth in a simple line. Though they still die in one hit, there's also just enough room to jump between the first two, allowing a good opportunity to play with the Jet Armor. While flying underwater, Mega Man cannot rise as quickly but also falls slower, meaning players can get more horizontal movement out of it for less fuel.
Most of the area is standard for a spike corridor, but the last image shows a good mix of enemies and terrain, as the lowest Gabgyo appears right as Mega Man is stepping off the previous platform, which could scare a player into jumping and hitting the low spikes here. Those spikes also make the last Wallblaster harder to attack.
The remainder of the area is nothing special, besides another reminder that shooting through walls is useful. The next section, however, includes a unique and baffling mechanic. The water is now on the ceiling, and the level slowly rises and falls.
As with normal water, we gain extra height by jumping in it, which means we need to wait for its lowest point to get the best jump. There's a couple empty screens here to give players a chance to figure out what's going on.
Choker Oh fires shots at various angles, aiming for Mega Man. It will also jump forward when attacked, and is affected by the water physics. This is a really cool situation, as it allows the enemy to have varied, non-random movement in a way other than the timing with which it spawns. The hole behind us also pulls double duty as an extra hazard and a fun way for players to kill Choker.
Choker's five health also makes the charge shot useful, as we can afford to spend the time building it up and will want to take Choker down before he moves much. The area builds on this by changing up the floor and adding spikes, with one long jump that forces an unarmored Mega Man to use the water correctly.
Pooker is just wasting our time here, as he won't appear again in this stage, so we have no need to learn how he works. Eddie and the large health are welcome though, as we haven't had any refills yet.
The floating cloud is Submarine Flier. Naturally, when it hits a wall or reaches Mega Man's position...
...it reveals itself as a submarine. These are dangerous in the deeper water, as they'll try to stay above Mega Man while throwing out arcing projectiles.
A player who allows both of them to reach the water here will have a tough time getting out. This makes the following blocks an odd choice, as the only thing the subs can do in the air is get in the way, and their shots only reach high enough to threaten the final block and area under the ladder.
A few SRUs come back to get in the way of our jumps, but the game warns the player by having one drop when we enter the screen. Squidon fills the role of the final guard, and the Jet Armor gives us the option to bypass him. This is another stage with an alternate boss door, but the designer decided (wisely, judging from the other stages) to forgo any attempt at a split path, so we only need to cross this gap to reach it.
While not very exciting, this is a stage that falls more on the side of safe than lazy. With the pelicans' fish vanishing into the water and the subs having little chance to show off their mechanics, there was a lot of room for improvement, but what's here is still decent. Pelicanu and SRU-21/P work well together on the first set of jumps, Gabgyo's speed helps make the simple spike corridor feel more dangerous, and Squidon is a solid enough enemy to cap it off with. The ceiling water gives the stage something memorable, and while the Power Armor is practically useless, the Jet Armor is fun to use underwater.