This first level doesn't really fit into the main story of the game. The canyon is merely an area where you can learn to control Indy and practice many of the moves you will need later in the game. Watch out for snakes and steep ledges which are about the only things that can kill you. Also be on the lookout for those 10 treasure items.
Head toward the valley and jump over the gap to the right. Climb the rocks until you reach the base of the ladder then climb it to the top. Cross this next area and pull the block from the wall two spaces. Move the block so you can climb on and use it to jump and hang on the edge of the alcove on the nearby wall. Pull up and enter to find the Silver Coins; the first of the ten treasure items.
Drop back down and walk through the hole where the block used to be. On the other side you can turn left and crawl through the low opening and head along the ledge jumping across the next two gaps. The second gap is long and you will need to grab the opposite edge and pull up. Continue forward until the canyon narrows and the right wall blends into a building.
Look up to spot a post sticking out of the wall. Walk to the end of the narrow canyon and use your whip on the post above and climb up. Swing forward (use jump key to swing) and continue. Ahead is an open area with a building across the way. A stone block is a short hop away but ignore it for now.
Drop down to the area below and go past the block toward the opposite room. Kill the snake in the doorway and enter the room. Take the Blue Gem from the niche in the right wall then exit outside and return to the stone block. Climb up and do a running jump to the next block against the building then turn and look up to spot the post you can use your whip on to swing to the other side.
When you land on the opposite roof you will crash through the ceiling and land in the room below. Just as you get a glimpse of some more treasure you fall through this floor into an underground river. Swim to the shore and climb out. Head to the ladder and climb up to the previous level where you can get the Gold Bar - the skeleton certainly doesn't need it. Ignore the ladder leading to the roof and jump back into the hole and into the water below.
Swim along with the current of this river until you plummet over the huge waterfall and land in the pool below. While you are submerged you may as well snag that Silver Idol from the underwater niche on the side of the pool. Surface and take a deep breath then dive down and swim under the falls into the tunnel.
When you exit the water at the other end of the passage you will be in a huge cavern. You can ignore the ladders on the far wall and instead, head for the greenish pit. Use the steps along the left side of the pit to make your way to the bottom where you will find another skeleton. Relieve him of his collection of Gold Coins then climb the tall stone steps to get back out of the pit. If you are adventurous you could climb those ladders to get back outside but taking the underwater tunnel is much safer and faster.
When you exit the pool at the base of the falls you will see a chopper fly over the canyon. You will also get a potsherd from the dig site. This isn't a treasure, in fact it is almost an insult to Indy's famed abilities. A pair of secrets are nearby; the first is down the dead end passage to the left. Head down there to find another skeleton and a Blue Gem. Head back out of this canyon and go left again down another dead end canyon.
A small alcove in the left wall of this canyon has a niche in the wall with a Red Gem resting on a ledge. Take the gem and return to the dig site. This time head left again up the stone steps. Climb up the first two blocks then look into the pit to spot a tunnel below.
Drop down and crawl through the tunnel to find a hidden room with a Gold Idol resting on a pedestal. Take the idol and return back to the step. Jump across to the opposite (higher) step then head left past the next step off toward the tree at the end of this canyon. Take the Gold Coins from the base of the tree then return to the steps and continue climbing up.
Jump up and grab the crack in the wall and shimmy to the left and pull up to the flat ledge. Turn and do a running jump to the opposite ledge and climb the ladder. Do another running jump to return to the previous side of the canyon then you can jump and pull up to the next highest ledge. Whip out those pistols and kill the snake that attacks you as you climb onto this ledge.
Your ultimate goal is to jump across and through the arched opening, but first you will want to climb the ladder on the nearby wall and enter the short dead end passage and get the final treasure on this level; the Blue Gem. Carefully climb back down and do a running jump and grab the edge of the arched opening and pull up and go through. Drop into the lower area and cross to the other side. When you climb out and enter the camp a movie will take over which outlines the plot of the main game. Get in Sophia's chopper and head off to Babylon.
(2) First Aid Kits
(1) Poison Kit