The first act takes place outside, in a sweltering desert area patrolled by Sandworms, Skorps and Rock'n Badniks. Little sand-falls should allow Sonic or Knuckles to progress up them by jumping, while others will automatically be run up. The loops here are different, because when the player goes through one, they circle for a few moments before being launched high into the air. Upon reaching the end of the act, a pyramid rises out of the ground and a Guardian (resembling the Egg Golem from Sonic Adventure 2) emerges to fight the player. The Guardian can easily be broken apart by a Spin Attack to the head, but will quickly reform and continue to attack. To defeat it, the player must lead it to the quicksand pit on the far left of the area and have it jump in. After beating this mini-boss, the player enters the pyramid.
The second act takes place inside the pyramid. Chains hanging from the ceiling throughout the level act as light switches, and the lights must be on or ghosts will appear to attack the player. Switches can be pushed to open doors to subsequent rooms, although they close after a short amount of time so the player must pass through them quickly. Some rooms have bricks sealed in the walls that release sand flows when broken, which raises the ground level in the room, allowing progression to higher floors but also causing a risk of crushing the player against the roof if they're not fast enough to keep up with the overflow.
Doctor Robotnik appears in a giant statue, though, he cannot be seen because the head area of the statue, where he sits in his Egg Mobile. This is the only vulnerable part, which must be hit twice in order to actually hit the boss. All other areas of the boss are covered with spikes, except for the back of the statue's hand. As the statue proceeds forward, its left hand will move to the front. The player can stand on the appendage and jump from there to attack.
In the Sonic the Comic series published by Fleetway Editions, the Sandopolis Zone is a desert Zone found only on the Floating Island. In this media, the Sandopolis Zone is filled with many ancient ruins, most noticeably the Lost Pyramid of Sandopolis, making it an ideal target for treasure hunters. The comic presented a fairly faithful adaptation of this Zone which first debuted in Sonic the Comic #47.
The entrance to Lava Reef from this zone is different between Sonic and Knuckles. Sonic goes into a tunnel and falls through a hole, but Knuckles runs right over it, even though the pre-released ghosts should indicate that Sonic has been there already.
In the first act, there are a couple pools of quicksand that, instead of killing the character, will drag the character down into another part of the level, usually revealing hidden items such as Super Ring. It is hard, however, to recognize the different quicksand pools since they all look alike (although ground below the pool can occasionally be seen) and they all behave in the same way. It is usually best to avoid sinking in any quicksand. The second act has only one of these non-deadly quicksand pools.
If the player goes to Act 2 in story mode, the act will be dark. However, if the player uses level select to enter Act 2 or restarts it, the act will start with light.