E2M1 Contains 5 secrets.

Secret1 : When you're between the two eye key doors, if you hop over the left hand side of the boat and turn to face the front of the boat there will be an item hidden in a corner.
Contains : Diving suit

Secret2 : If you swim around under the front of the main ship, there will be a hole above you in the ice you can swim up in. There will be a small space in the ice.
Contains : Life seed

Secret3 : Search the ice around the right hand side of the ship, there will be an icy passage.
Contains : Voodoo doll

Secret4 : This is an easy one. When you find the skull key underwater, surface above the water and look to the corners. One of them will have a gap with a spinning object inside. Go inside this space.
Contains : Life seed and super armour

Secret5 : In the room with the fire key and all the boxes, check behind all the boxes. There will be a thin space where spiders attack you from. Look in there.
Contains : Doctor's bag

E2M2 Contains 2 secrets.

Secret1 : There will be a room with a broom in the cupboard, a bookshelf and a calendar with a girl on. In this room there is a grey cupboard. Push the cupboard and it slides away, revealing a secret passage.
Contains : Super armour and a box of TNT

Secret2 : In the large area with all the planks of wood stacked there is a small hole in the side of the structure. Continue searching all over on top of the planks until you find a hole in a large wall.
Contains : A box of flares and a box of TNT

E2M3 Contains 5 secrets.

Secret1 : When you first find the fortress-like structure when you exit the maze, look to your left. A piece of the hedgemaze just won't look right. Move up to it and open it. These are double doors cut into the hedge.
Contains : Basic armour

Secret2 : Inside the bloated butcher's house (where you get the skull key) is a pair of jumping boots. This house actually has a second floor. Activate your jumping boots and jump up into the roof of the house when you're inside. You'll see the ledge.
Contains : 2 proximity mines

Secret3 : There is a small shack outside the bloated butcher's house (where you get the skull key). It contains tools and various objects. Push the left hand wall and it will slide open.
Contains : Doctor's bag

Secret4 : When you're in the large pool area, stand on the diving board and a small panel will open inside the pool.
Contains : Life seed

Secret5 : Outside the small cosy room with all the wine glasses and stuff there is a path that leads out of a gate you can't exit through. On the side of the path there is a spade shoved into the snow. Push the spade and a hedge will open nearby. Inside there is a frozen innocent. Kill him and he drops your item.
Contains : DEATH MASK

E2M4 Contains 19 secrets (out of 17!) and the path to the secret level!

The boys down at Monolith made a mistake in this level. I have found 19 secrets out of 17, I believe these are all of them.

Secret1 : In the maze in the beginning there is a wooden post. Push the post and it will lower. Climb on top and it will take you to the top of the maze look around on top of the maze.
Contains : A box of flares

Secret2 : You'll notice a spinning object at the top left of the hotel you enter. Walk along the snow back at the steps until you reach the object.
Contains : Basic armour

Secret3 : When you first enter the hotel. Move forward and to the left.You'll find a brown texture with a dagger on. Press it and it opens to reveal a secret chamber.
Contains : A box of shotgun shells and a box of TNT

Secret4 : One of the passages to the dining room has a painting of the insides of a human. Push the painting and a wall behind you will open.
Contains : A box of TNT, a full drum of bullets and body armour

Secret5 : In the room with the cupboard with the phantasm, shirts and fire armour in, push the bookshelf on the left of the room and it lowers.
Contains : Tome (see below)

Secret6 : In the room with the cupboard with the phantasm, shirts and fire armour in, step onto the bed and the back of the cupboard will open.
Contains : Nothing, but gives access to a secret passage that allows you to reach other areas of the level.

Secret7 : Push the grandfather clock in the passage (listen for the ticking sound) and it will rotate and grant access to a secret passage.
Contains : Nothing, but gives access to a secret passage that allows you to reach other areas of the level.

Secret8 : In the room with the canopy bed, step on the bed and a passage will open at the top of the bed.
Contains : Nothing, but gives access to a secret passage that allows you to reach other areas of the level.

Secret9 : In the part of the library with the candle stands. Look at the bookshelf before you enter the other half of the library, it will appear discoloured. Press it and it will lower and is in fact an elvator. Let it take you to the top.
Contains : Tome (see below)

Secret10 : If you go up the lift in the library (see above) once you collect the tome, look behind you. There will be a door. Open it and it will allow to reach the top of the bookshelves on the other side of the library.
Contains : Two cans of gasoline.

Secret11 : Once you've collected the two cans of gasoline (see above) jump to the top of the bookshelf on the other side. Push the bookshelf on your left and it will open to reveal a secret passage.
Contains : A box of flares, a box of shotgun shells, a full drum of bullets and guns akimbo.

Secret12 : One of the rooms beyond the fire key door is a bathroom, where the zombies come out the bath to attack you, jump through the mirror.
Contains : Nothing, but gives access to a secret passage that allows you to reach other areas of the level.

Secret13 : In the dagger key room beyond the door that needs the dagger key, there is a bookshelf. Open it.
Contains : A box of TNT and three spraycans.

Secret14 : In the secret mentioned above, there are some wooden beams on the side. Jump on the wooden planks.
Contains : Doctor's bag

Secret15 : In the room where you get the moon key. Step into the fireplace and jump up the back of it. There will be a small ledge with items on.
Contains : Guns akimbo, voodoo doll, a box of shotgun shells and a box of TNT

Secret16 : In the side of the library that holds the candle sticks. There are three bookshelves that are further back than the rest. Push the one on the far right.
Contains : Nothing, but gives access to a secret passage that allows you to reach other areas of the level.

Secret17 : If you go down the secret passage you'll find a bloody door, open it and move into the room. Another way of getting in is if you blow up the picture of the woman in the section of the library that has the candle sticks, you will be able to access this room through a hole.
Contains : 4 shotgun shells, a tome (see below), 2 spray cans, a full drum of bullets and limited invisibility

Secret18 : If you go down the secret passage, you'll eventually find a smooth wooden surface at the very end. Open it and you'll find a teleporter.
Contains : Nothing, but gives access to other parts of the level.

Secret19 : In the spider key room, if you stay on the balcony, a part of the grey wall will appear red. Open it and there is a teleporter. Secret 18 and 19 are linked, so if you find the one secret you've found the other.
Contains : Nothing, but gives access to other parts of the level.

Secret level - in this picture is the hall where you get the moon key.
In the level there are five tomes, each is a piece of the sequence that creates this demonic portal. Once you've collected all five tomes, step into the blue flame and you'll teleport to the secret level. The tomes are found in the following locations:
1 on top of the bookshelves in the library
1 in the secret room at the end of the secret passage
1 behind the bookshelf in the bedroom (see secret 5)
1 in the fire key room with the bed, on the bedside table
1 on the table in the dagger key room

E2M5 Contains 8 secrets and a super secret.

Secret1 : The small house that requires the skull key that you see in the beginning of the level has a small hedged space on the right. If you jump into this space, there will be prize.
Contains : Beast vision

Secret2 : When you walk up the second flight of stairs in the level, with the hedges for walls, one of the hedges on your right will be discoloured, push it and it will open to reveal a secret passage.
Secret3 : If you enter the library through the passage with the curtains hanging down, turn to your right and push the bookshelves, one will lower to reveal a prize.
Contains : Guns akimbo

Secret4 : In the large library with the couch in front of the fireplace there is a secret in the fire. Step into the fireplace and push the back wall. It will open.
Contains : Fire armour

Secret5 : In the large library with the couch in front of the fireplace there are a few bookshelves on the opposite side of the very tall bookshelf. One of them is discoloured and is in fact an elevator. Push it and it will lower, allowing you access to the tops of the the shelves.
Contains : A box of TNT, a full drum of bullets and 2 sets of 4 shotgun shells

Secret6 : In the library with the green walls and the hanging woman surrounded by bloated butchers. Push the bookshelf and it will slide back, revealing a secret passage.
Contains : A box of shotgun shells and limited invisibility

Secret7 : If you face the spider key door and turn around, there will be a bookshelf approach the bookshelf and push it. It will flip around and you with it to reveal a secret compartment hidden behind it.
Contains : Doctor's bag, spirit armour and a voodoo doll

Secret8 : This takes place near the pool with the spider key next to it. If you leap along on top of the hedgemazes you'll eventually get the 'You found a secret.' message when you step on the correct one. When you read this, look at the nearby wall - a small chamber will have opened.
Contains : Super armour

Super secret - This picture shows what appears to be a useless piece of ground. This is in fact the path to the super secret. This is the maze that has the zombies in and has all the blood sprayed all over the walls. This is very tricky, but when you first enter the maze, duck and push the wall in front of you and keep moving and pushing. You will eventually press a teleporter and warp away to a secret room. My crossair is on the exact spot you need to push in this picture.
Contains : 4 remote detonators, 4 proximity mines, super armour and a voodoo doll

E2M6 Contains 5 secrets.

Secret1 : In the ice passage before you reach the side of the mountain, there is a jump you have to make over a small, but very deep pit. On the side of the ledge you jump off of is a small ledge that is quite easy to spot.
Contains : 4 shotgun shells and a few bullets.

Secret2 : One of the islands at the deep pit has a surprise hidden on it. You can either use your jumping boots or simply jump to reach it.
Contains : Life seed

Secret3 : When you're travelling along the mountain pass, the end of it holds two ways to go. A high way and a low way. Take the high road and you'll find yourself on a ledge with cultists. On the far wall there will be a crack. Use explosives to blow open a secret chamber.
Contains : Jumping boots and 2 spray cans

Secret4 : There are two ways to access this secret. Either you can go through the secret above (there will be another crack in the wall) or you can collect the skull key and use jumping boots to jump through the hole in the roof.
Contains : A sawed-off shotgun, a tommy gun and a box of TNT

Secret5 : In the building that requires the skull key, there is a small room with a hole in the roof. Use your jumping boots to leap into the hole in the roof.
Contains : 3 remote detonators and 2 proximity mines

E2M7 Contains 2 secrets.

Secret1 : When you finish riding the mine cart and the earthquake happens. Jump to the other side of the gorge and turn right. Walk towards the wall and there is a well concealed passage.
Contains : 2 sets of 4 shotgun shells and a life seed

Secret2 : When you pull the wooden beam to access the underwater passage a second stone door will open on the opposite side of the body of water. This will lead to a place to surface that leads to a secret chamber
Contains : A box of shotgun shells, a full drum of bullets and a diving suit.

E2M8 Contains 0 secrets.

How dull.

E2M9 Contains 2 secrets.

Secret1 : In the very first body of water, swim around. Around one of the corners will be a dark, open space.
Contains : Super armour and a doctor's bag

Secret2 : When the cracks open and you leap into the water, there will be a small space that connects the two bodies of water together. Investigate it.
Contains : A box of shotgun shells and a full drum of bullets