im stuck on level 4. and u?

I'm assuming you have moved on since this thread, but just in case...
FOUR WAYS OF MYSTERY
Primary Objectives; Locate the Recluse Dolphin, Distract the Giant Eel with a Giant Manta Ray

***The large Crystal columns that are found in the tunnels will replenish your air as long as they have a dancing light inside them. Any Oysters that you find in the level will replenish your health. To release these goodies, simply sonar the item in question. The crystals will release the light and it will travel over Ecco to restore his air, and the Oysters will open up to reveal a Pearl. Collect the pearl and your health will be restored.***

This level takes time & patience. Try to rush it and you will most likely end up in a wrong tunnel with no idea where to go. From your start position, travel into the central chamber and collect the Air Crystal. This will give you the ability to use the Air Glyphs which will extend you air supply, and for this level you need as much air as you can get. After collecting the Air Crystal, turn so that you are facing a purple Guardian Glyph and swim towards and past it until you see the cavern wall.

Along that section of wall will be a tunnel with a small Eel hiding in the top of the tunnel entrance. UNLESS YOU ARE COLLECTING VITALITS THIS TUNNEL HAS NO USE TO YOU! With that tunnel facing you, turn 90 degrees to your right and carry on swimming along that sidewall (keep an eye on that air meter) until you see a section of the wall turn light brown and looks like it is made of old brickwork. It is high up on the wall, much higher then the first tunnel, and has Sea Anemones in the entrance. You can stun these into retracting by sonaring them.

A small way down this tunnel is an Air Glyph (YAY!), which will refill your air supply and double its length from a full position as well. After collecting the Glyph continue into the tunnel until you reach a Purple Crystal Column. From here you can go left, right or ahead. In the right hand tunnel is a Power Sonar Glyph, which you will need on your return (Oh yes, you will come back here later in the game).

The left hand tunnel contains the Recluse Dolphin. If you travel all the way to the end of the tunnel, ignoring the left hand turn about half way down the tunnel you will enter an area with the Recluse Dolphin who will teach you The Ray Song if you go back to the main area of the level and bring him the LARGE Blue & Yellow Fish. The forward tunnel is just a dead end, but it has an air current to restore your air if you are running low and have already used the Crystal restore.

Once you have the Ray Song, exit this section of tunnels as quickly as possible and go back into the central chamber. Head towards the tunnel where you started and when you are looking towards your start point, turn left 90 degrees and follow this wall until you find a very low tunnel entrance. This is called the 'Red Tunnel', as it has a Red Crystal Column in it (remember the purple one?). Once you reach the Red Crystal Column you can go ahead or left. The left tunnel serves no purpose except to waste your time and air, both of which are precious in this level.

If you go straight on down the forward tunnel you will come to a pool with sharks in it and a LARGE MANTA RAY (you need him in a minute). Kill the sharks. Replace any energy you may have lost in the fighting and collect the Air Glyph (helpful Guardian again!) that is in the pool. Make sure that you are facing the tunnel and the Manta Ray is between you and the tunnel. If you sonar the Manta Ray he will swim towards the tunnel, and start swimming down the tunnel. Stay behind him and keep sonaring him until you exit the tunnel.

Once you exit you need to aim the Ray about 45 degrees to the right of the tunnel you just came out of, as this puts him swimming towards the Giant Eel in the roof that would usually eat Ecco and end this fun rather early. If you're still not quite sure where to aim him, just look for a floor-to-ceiling column of rock. The Giant Eel is hiding behind this. Make the Ray swim towards this area and as soon as you see the Eel dive out of the roof, CHARGE like mad past him and into the tunnel beyond. Think that's it? OH BOY, ARE YOU WRONG. We can't let all these fun and games end quite so quickly, can we!

Head down the tunnel (beware, its LONG) until you get to a 'collar' of rock similar to the one that the Air Glyph was in. Beyond this is a small air column that you can refresh your air with. Just beyond this you will see another tunnel, but it will have a strong current, which will stop you progressing. OH NO, no Vigour Glyph, what do we do! Never fear, here is the answer. The rocks above this tunnel are loose, and if you nudge one it will fall down the tunnel and block the current BUT you have to follow the rock down, as it will not block the current permanently.

Once you are past this the tunnel will split into two. The right hand tunnel has the fish that cure jellyfish stings, so if you do get stung here, go right and heal yourself. The left tunnel will lead to a four-way junction with a VERY BIG Blue Crystal Column in the middle of it. The ONLY tunnel of importance here is the right hand one. If you travel down this tunnel a short way it will split into two. The right hand side has an Oyster if you need to replace Ecco's energy. If you don't need to head to the right then take the left hand fork and swim like hell as from this point on it is a straight race between you and Ecco's lung capacity.

Keep travelling down the tunnel, ignoring any other turns, as they are of no importance to you whatsoever. Eventually, after what seem like miles of tunnels, you will see another rock collar (remember them?), which signifies the end of the level. Travel through it and keep swimming until a cut-scene takes over and shows Ecco swimming upwards and back to Perils Of The Coral Reef (Nope, I'm not kidding).

VITALITS
I. Turn left in the first tunnel to find it in the roof of the dead end
II. Above the waters surface in the Recluse pool
III. Just below the waters surface in the middle of the pool with the Manta Ray & sharks in it
IV. At the end of the first right hand tunnel within the 'Exit' tunnel, with the Oyster in it
V. In the roof of the central chamber, near the Air Crystal pick-up point [only accessible by using the Power Of Sonar]