Before leaving, Sebastian decided to stop and go through an adaptation that he hardly paid attention to before since he bought it due to the conditions of his environment and a ton of other reasons.

  [You have triggered Adaptation: Map.]

  Yes, his map adaptation was one of the few add-ons that he neglected a lot in his body since transmigrating into this world.

  It was not his fault, it's just that the always eventful situation of his surroundings left him with little time to pay attention to it.

  As soon as he triggered the adaptation, he felt like a huge virtual map appeared in his imaginary vision.

  The map currently had only 2 regions, a region represented by the normal green color of the Green Mist Sea and the other that was tainted with a deep redness that was glaring to the eyes.

  These 2 regions were his previous location in the wide expanse of water and his current location in the ocean volcano.

  As this was the only location that he's visited since transmigrating into this world, they were also the only places recorded on his map.

  The mechanisms of the map were that as he explored the world, the explored regions would be indicated in the map to enable him to easily locate them when needed in the future.

  For him to narrow the map down to get more accurate directions, all he needed to do was focus and the map would respond accordingly like he could zoom it similarly to a camera.

  It was just like an advanced version of google maps in his previous world.

  On the map, he could see a great distance between his previous location and this world of fire. Though it was in a miniaturized version, Sebastian guessed that the actual distance was probably hundreds or even thousands of kilometers.

  To get more accurate statistics, he had to experiment with it himself.

  His conjecture left him feeling a little depressed. Apart from the varied type of sea creatures that were here, in every other facet, he preferred his previous water region than here.

  Well, a beggar was not a chooser Afterall. He decided to follow his legendary second love again, which was ignoring things.

  After thinking about it, he decided to give these 2 main regions a name on the map as he would probably explore more regions after here.

  [Unique Region name has been given by host!]

  [Explored Regions: Wardrobe Ocean Volcano; Leroy Cave Expanse.]

  There was a tendency that he would explore more ocean volcanos in the future, so he simply named this region with the characteristics that were more glaring to him, the wardrobe-like shape of the large circular cliff walls.

  For his previous expanse, he simply named it so because the Leroy Clan's cave was located there which was the best landmark naming to him.

  After completing this important task, he finally turned to explore deeper into the seamount but on instinctively activating his electroreceptors again, he was surprised as he found a hidden hole below him.

  Looking down, he found only rocks but he was sure that a hole was hidden there due to the penetrating powers of his electroreceptors.

  Before going closer to check it out, he quickly made some conjectures.

  The Giant Worm fought with the Giant Crab here without fearing for its life, and when another predator came, 2 other Giant Worms suddenly appeared.

  Connecting this with his discovery, he confirmed it and made a guess. Just like the city of eels that he encountered before, there was likely a city or at least a town of Giant Worms below here.

  Without hesitation, he swam down to check out the rocks blocking the entrance but he was stunned as he encountered no resistance.

  [Host has broken through the effects of an illusion magic.]

  "Illusion magic?" Sebastian was once again stunned.

  When he looked again, he noticed that the rocks were gone and a hole leading deep into the seamount was what presented itself before him.

  Inside the hole was clearly darker, but the redness of the surroundings illuminated it a bit, though in an ominous manner.

  Filled with curiosity now, Sebastian decided to explore it. Of course, before entering, he rapidly formed a contingency plan to prepare a way out for himself in the case he met trouble that he could not easily escape from.

  [You have activated skill: Triple Reverse Swim.]

  Cautiously, he slowly swam inside the hole that led into a large tunnel below. Due to the Giant size of the Worms, the hole was big enough for him to enter, making things a lot easier.

  [You have triggered Adaptation: Camouflage Skin.]

  As he entered, he triggered this adaptation again to adjust the redness of his skin to better blend with that of the hole. Then, he continued his exploration down.

  As he went deeper into the tunnel, he was surprised to notice that no Giant Worms was lurking in the surroundings. What even surprised him more was that he started noticing the handwork of humans in play.

  The deeper he swam, the more he deduced that this was a cave tunnel dug out by human hands or equipment.

  "Did the Atlantians once live here? Or are there other humans in this world?" He soliloquized curiously while still being alert.

  From barely containing him in, the tunnel slowly widened to almost twice his size. A few seconds later, he finally arrived at what seemed to be the end of the tunnel.

  On getting there, the darkness was now much more significant but he quickly noticed the 2 Giant worms that were slithering in the water opposite him.

  Besides these 2 Worms, he discovered another thing- this was a huge network of underground tunnels and passages and they were all built in the styles of humans, clearly not natural.

  From his position, 5 other tunnels extended in different directions.

  As the Worms didn't discover him because of the darkness of the cave, he was able to leisurely observe more. Looking towards the depths of one of the 5 branching tunnels, he discovered what seemed like a hall.

  2 large pillars stood in the middle of the hall, and piles of human skeletons were arranged on top of each other there.

  Looking at the other 4 directions, he saw the same thing. Putting all these together with his knowledge from earth, he came to a conclusion.

  This was a Catacomb.