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Sonic & Knuckles
Lava Reef Zone

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Enter the biggest, hottest Zone on Floating Island! Beware of exploding rocks and Toxomisters that poison the air!

— United States instruction booklet, Sonic & Knuckles[1]

Lava Reef Zone (ラバーリーフ ゾーン[2] Rabārīfu Zōn?) is the fourth Zone of Sonic & Knuckles, and the tenth of Sonic the Hedgehog 3 & Knuckles. It is set inside of a giant volcano on the Floating Island. Unlike most Zones in Sonic & Knuckles and Sonic the Hedgehog 3 & Knuckles, Lava Reef Zone is divided into three Acts instead of two, with a boss fight at the end of the first and third Act.


Said to be the largest and hottest Zone on the Floating Island,[1] Lava Reef Zone takes place inside an active volcano on the Floating Island, spanning through an network of abandoned mines and the volcano's magma chamber. The ground here is made of various large rocks, while some machinery can be found quite often. Most areas in this Zone are flooded with lava, with some platforms on them.

Lava Reef Zone Act 1 comprises an area set in a cavernous chamber deep underground. Large, dark green pillar-like formations of rock dominate the foreground, and speleothems dot the background amongst an eerie reddish glow. A vast plain of freshly-cooled magma stretches far beyond into the horizon. Pipes festoon the walls and floor, and the inactive Death Egg can be seen on the chamber's roof during Sonic and/or Tails's playthrough, sitting beside a pillar in the near background. However, the Death Egg is absent during Knuckles' plathrough. In addition, a flowing lava fall makes up the background of the site where the player fights Heat Arms.

Lava Reef Zone Act 2 is mainly composed of a network of caves with the corners and walls that are curved and smoothed out. The stones that make up the environment are all blue-colored, with various crystals on them that glow in several colors. There are also various signs of light blue machinary, and the ground is covered in green platforms. At the very top, the Death Egg can be seen in Sonic and/or Tails' playthrough, even closer to the camera than in Act 1. However, the Death Egg is absent during Knuckles' plathrough. At the end of the Act in Sonic/Tails playthrough, the boss site undergoes a few major differences: the Death Egg is now extremely close to the player's perspective, taking up nearly the whole top of the screen. When the Death Egg activates its laser attack, the background gains a fiery red tint, with most things taking on a reddish or orangeish tint; a mirage effect caused from the extreme heat also causes the image of the background to "wiggle" from side to side, just before the Hot Mobile fight begins.


Having fallen into a hidden pit in Sandopolis Zone, Sonic and Tails find themselves falling into and landing in Lava Reef Zone. There, they make their way through the magma-filled mouth of the volcano before facing off against Heat Arms. With the magma cooling after defeating the robot, Sonic and Tails make their way further into the volcano, until they reach an area where the magma has been warmed up again. There, they are sent tumbling into the inner magma chamber by Knuckles with a large boulder, where the Death Egg itself reactivates, superheating the magma again. Robotnik then appears to eliminate the duo with his Hot Mobile. After Sonic and Tails defeats the Hot Mobile however, the magma cools for good, and Sonic and Tails proceed into Hidden Palace Zone.

A while later, Knuckles enters Lava Reef Zone from another direction and makes his way through said Zone, dealing with Heat Arms at the halfway point. After that, he proceeds through the Zone until he reaches Hidden Palace Zone.


In Act 1, common gimmicks include platforms that break and fall away (often into magma) if stepped on, spirals and ramps that propel the player over magma pits, holes that shoot damage-inflicting fireballs horizontally in a straight line, and doors that can only be opened by pressing a nearby Switch. A section of Act 1 includes a long, slanted path that releases a large iron ball if the player travels through it.

Gimmicks found in Act 2 include geysers that shoot streams of fire every few seconds, pads that launch small spiked balls into the air at audible time intervals, large steel blocks that move up and down or side to side, high-speed warp tubes, and rotating blue rods with bars on them. If the playable character grabs these bars, they will latch on and move around and around with the rod; Spin Jumping propels them either up or down, depending on if they were moving up or down when the player presses A Button (Sega Genesis).svg/B Button (Sega Genesis).svg/C Button (Sega Genesis).svg.


Act 1

Act 1 begins with Sonic and/or Tails falling into the Act itself, landing on several breakaway platforms before reaching the bottom and proceeding into the Zone proper. When navigating the Act, watch out for machines armed with spikes on their underside that will rise up before crashing back down, which can crushing the player.

When arriving at the slanted path with the iron ball coming down it, the player cannot resort to Spin Jumping over the iron ball as it is impossible to get over the iron ball without taking damage. Instead, the player must dodge it by crouching in the small pit at the end of the path and waiting for it to pass.

After navigating through the zone, the player must then face the Act's boss, Heat Arms.

Act 2

After the player defeats Heat Arms, much of the magma hardens and cools into a solid state, rendering it safe to touch and walk on.

After moving through the complex system of caves, the player proceeds up a staircase followed by a large, flat platform that breaks away when stepped on, and another set of stairs. There, the player again encounters Knuckles, who laughs smugly and pushes a large boulder into the playable character, taking them with it as it falls into the boss room.

If playing as Knuckles instead of Sonic/Tails, he does not enter Act 3. Instead, Knuckles proceeds past the site where he drops the boulder on Sonic/Tails and travels through a tunnel into Hidden Palace Zone.

Act 3

Similar to the beginning of Act 1, Sonic/Tails falls into the boss room, where the Death Egg awaits; suddenly, the once inactive spacecraft activates the laser cannons in its eyes, engulfing the entire screen in a bright flash. When the flash dies down, the once solidified magma has reheated into a molten state by the Death Egg's attack, which has also caused some of the ground to become fragile. Afterward, Dr. Robotnik appears in the Hot Mobile and releases a barrage of missiles. Now, Sonic/Tails must make his way by jumping from platform to platform while avoiding the raining missiles as the screen forcibly advances forward as Robotnik watches in the background before retreating into the magma for the boss fight later. After reaching a Star Post, Sonic/Tails then has to traverse across sparse footing down a fall of magma, where he can find a Lightning Shield and a Flame Shield positioned on stationary ledges. At the foot of the magma fall, the player encounters Dr. Robotnik in the Hot Mobile. After the Hot Mobile is defeated, the lava will once again cool down, allowing access to Hidden Palace Zone.


Act 1

Main article: Heat Arms

The boss of Lava Reef Zone Act 1 is Heat Arms, a giant robotic hand. During the battle, Heat Arms will use two tentacles to attack the player from the edges of the screen. Each one takes four hits to destroy, and each one fires three shots in three different angles before both retreat off-screen. Heat Arms itself will then track the playable character's movements before slamming down to crush the playable character. This is when Heat Arms can be damaged before it recovers and retreats to repeat its attack pattern. Six hits are needed to destroy Heat Arms. If the tentacles are still active when Heat Arms is destroyed, they will be destroyed as well.

Act 3

Main article: Hot Mobile

The Hot Mobile, from Sonic & Knuckles.

The boss of Lava Reef Zone Act 3 is the Hot Mobile, a modified Egg Mobile that can be submerged in magma. This boss is thoroughly protected by protruding spikes. Dr. Robotnik will appear on the right and left sides of the screen, rising from the magma. Creating a sloping current in his direction, he will attempt to make the platforms the playable character is standing on run into his protected machine, while constantly shooting spiked mines in order to add another danger to the player hopping from platform to platform; ironically, his own mines will follow the current's flow and damage him. Eventually, after fourteen mines hit his machine, the scientist will be defeated.

In other media

Sonic the Comic

In the Sonic the Comic series and its spin-offs published by Fleetway Editions, Lava Reef Zone is a Zone set in the volcano on the Floating Island. Sonic and Knuckles pass through here after escaping from Sandopolis Zone. There, they found the eath Egg II sitting in the volcano's funnel. A squadron of EggRobos soon after arrived, but were defeated by Knuckles, who proceeded to the Emerald Chamber with Sonic. Later, Knuckles would return to Lava Reef Zone to rescue a boy named Jake from an Eggrobo.

Archie Comics

Main article: Lava Reef (Archie)

In the Sonic the Hedgehog comic series published by Archie Comics, Lava Reef Zone was a location on Angel Island. It was originally the Fire Ants' place of residence until the Dark Legion came and turned it into their hiding place. Sonic, Knuckles, and the Chaotix later visited Lava Reef when they went to go rescue Locke from captivity.


  • The level background music of Act 2 is recycled and used again for the succeeding Zone, Hidden Palace Zone.
  • The boss segment in Act 2 is considered to be an Act 3 of Lava Reef by many fans since the player can restart from the beginning of the boss if they die instead of having to restart from the Act itself.
    • Additionally, in the game's Level Select, the boss segment is listed as the third Act of Lava Reef Zone.
    • Hidden Palace Zone is listed as the fourth Act of Lava Reef Zone in the game's Level Select.
  • Lava Reef Zone appears as a part of the Sonic the Hedgehog Level Pack in Lego Dimensions.





Name Artist(s) Length Music Track
"Lava Reef" Tatsuyuki Maeda, Tomonori Sawada, Sachio Ogawa, Masayuki Nagao, Masanori Hikichi 1:27
N/A (Lava Reef Zone Act 2 theme) Masayuki Nagao 1:43



  1. 1.0 1.1 Sonic & Knuckles (Sega Mega Drive) United States instruction booklet, pg. 13.
  2. Sonic & Knuckles (Sega Mega Drive) Japanese instruction booklet, pg. 35.

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