Red Cavern
The Red Cavern section is one of the longest uninterrupted stretches in the game. You may need to use the slider bar below the map to see all of it. You arrive through door S in the center of the lower portion of the cavern. It turns out that the second Goonie is not far at all from your arrival point, so make her your first stop. Head all the way to the right to door A, making use of the floating platforms where necessary. Do your best to avoid getting hit by the down pour of the waterfalls.
Door A
From the Red Cavern, you will arrive in the room on the left. You must go right once, and down to pass through to the front layer.
Freezer B
You will arrive in this icy region of the front layer through door A. There is nothing of interest to the right, so head left to door B. Note that you will slide across the ice in this section, and even along the moving platforms, so be very careful as you move about. Watch out for axe throwing Eskimos and icicles that drop from the ceiling.
Door B
The first room you arrive in contains a hint baring safe. You can use a key to unlock it, but it's not recommended if you are low on keys. Highlight the space between the parentheses to read the hint: (BE CAREFUL ON BRIDGE NOT TO LOSE BOOMERANG.) Pass through the door on the right. The room will look empty, but if you hit the back wall with your hammer, a door will appear. Open the door, and you will find the second Goonie trapped in her cell. Use a key to rescue her, and you will now have four energy bars.
There is nothing left to do in this section, so simply return to door A, and head back through the rooms to return to the Red Cavern. Now return to your starting location at door S, and climb up the vine to the screen above. At the top of the vine, you will arrive at door C. Enter it now.
Door C
You will arrive in the left room. While the back and right doors are the only two visible to you, you should never discount the chance that there might be a door behind the "camera." The fact is, is you choose "GO," and press down, you will return to the front layer of the hideout. But before you do that, there are two important things to investigate. First check out the room to the right. Inside you will find an old woman who is not very friendly. The truth is, she has something you need, but the method to obtain it from her is rather… unconventional. Read the spoiler below to learn her secret. Once you're done, return to the left. The fact is, you can hit walls even if they contain a door, to see if an item is hidden in the room. If you hit the back wall above the door, a non-essential, but useful item will appear: the 
Transceiver. This item can be used in any room, and it will pick up clue messages from other Goonies, as well as from Konami, and Konami related characters themselves such as Simon Belmont and Twinbee (renamed Stinger by Konami of America). Grab the Transceiver and head down to the front layer.
The old lady has an item that is not necessary, but quite valuable to you. She has a 
Candle which you can use to light up dark rooms so that you can visually analyze the contents of the rooms. But you'll have to convince her to give it to you. In a rather unusual move for an early Nintendo game, you'll actually have to beat it out of her. Choose to hit her five times. Each time, she will complain, but on the fifth hit, the candle will appear for you to take.
Orange Cavern A & Freezer A
Through door C, you will arrive on the right side of the orange colored cavern. There is a door to the left, door D, and you must remain on the upper path to reach the floating platform that will carry you to it. Press up when the platform brings you in front of the door.
Door D
There are two benefits to visiting this door. One is obvious, and the other is hidden. You will enter through the lower left room. When you arrive, it will be pitch black. If you have obtained the Candle, you can use it at this time to light it up. There's a door ahead, and a door to the right. The room to the right contains nothing but another door, but the room ahead contains the one and only Konami Man! Every time you visit Konami Man, he will restore all of your missing energy. It's very wise to remember Konami Man's locations (there's more than one) in case you are in danger of dying. There is one more room to the right. Once again it will be pitch black, and while using a candle will help, it's not necessary. All you need to do is hit the back wall with your fist, and a second 
Keyring will appear, increasing your maximum keys to 4. Be sure to collect it before you head back outside.
There is nothing left in this Orange Cavern to investigate, so ride the platform back to the right, and return to the Red Cavern through door C. Climb back down the vine to door S, and start making your way to the left end of the lower portion. This time, your destination is door E. You can take either the upper route via the floating platforms, or the lower route.
Door E
This solitary room starts out pitch black. It's not important to light it up, as it only serves as a method to cross between the Red Cavern in the back layer, and the other icy area in the front layer. Press down to arrive in Freezer A. You will arrive near the center of the top portion at door E.
Once again, there is nothing of interest to your right when you arrive, so head to the left. You will arrive at a platform with a ladder that extends to the screen below. Climb down the ladder, and start making your way across the ice to the right until you reach door F. Watch out for the tougher enemies like the Eskimo, the walrus, and the polar bear.
Door F
Although you will have to return to this door at a later time in order to rescue another Goonie, this is your opportunity to collect two very valuable objects that will help you in your quest. One is out in the open for you to collect, while the other is very well hidden. You arrive in the bottom room. Use the candle to light it up if you like, but all you will find is a door ahead. Go up to pass through it. You will enter what looks like an empty room with doors to the left and right. Before you investigate the other rooms, try tapping the back wall with your hammer. This will make a safe appear. Normally, the contents of safes don't always merit the use of a key, but this hidden safe does. Open the safe and you will find a useful tool, the 
Glasses. You will see their utility shortly. If you pass through the left door, you will arrive in a room with a hole in the floor filled with water. If you had Scuba Gear, you could investigate it, but you don't yet. If you investigate the door to the right however, you will see a terrific weapon, the 
Boomerang, simply lying on the floor, free for the taking. Grab it. You will notice a door ahead, but if you look inside, you will simply find a harmless Eskimo. Head back out to the Freezer, and don't forget to equip your new found Boomerang.
With the Boomerang equipped, you will need to take some time to learn how to use it properly. It may seem slower than the yo-yo at first since you can fire it as frequently, but it travels much farther, so you can attack from a safe distance, and it hurts enemies coming and going, so you're more likely to do greater damage. There's nothing else in this Freezer section for you to explore, so return to door E up above and head back to the Red Cavern. Once you arrive, climb the nearby vine up to the upper section, and head left to door G.
Door G
This door puts your investigative skills to the test. Once you pass through this door, you will arrive in a pitch black room. However, lighting a candle won't reveal much. It seems empty, and every attempt to hit the walls with your fist or hammer result in nothing. However, if you managed to get a hold of the glasses from door F, then you will be able to discover the value of this room. Use the glasses, and a door will appear to the back. Through the door, you will find an old woman who voluntarily provides you with a 
Helmet, which will automatically protect your head from falling objects, a valuable defense item. Head back outside.
It would appear that there is only one door left to explore, and that is door H all the way to the right. In order to get there, you'll have to travel past door C which you visited earlier. On your way to door H, there happens to be a door hidden in the wall with no evidence of its existence. As you ride the floating platform that moves up and down in the path of a waterfall before door H, push up. When you reach the right location, and door will appear at the "!" mark and you will head inside.
Door !
Lo and behold, the door is an entrance to a Konami Man. He will restore your energy for you. That is all you will find behind this hidden door, but it is valuable to know. Note that if you ever hit Konami Man for any reason, he will refuse to restore you health for the remainder of the game! When you exit out of this room, be sure to press and hold left so that you land on a platform. Otherwise, you will fall right through the gap in the floor and lose a life. You are likely to be hit by the waterfall as soon as you leave.
Continue to make your way to the right to arrive at door H. Watch out for the scorpion that typically guards the small area where door H is found.
Door H
This room serves as the transport between the Red Cavern in the back layer and Orange Cavern B in the front layer, where you will begin your journey for the third Goonie