But Xiao Yi and his companions didn't flinch. Even in the face of such a perilous situation, not a trace of fear lingered in their eyes. As the giant octopus lashed out its spiky tentacles and the strange fish spewed toxic slime, Xiao Yi quickly calmed down, his mind racing as he pondered a countermeasure. He called out to his companions, urging them to remain calm and not panic. Encouraged by his words, they too rose to the occasion. They worked closely together, cooperating with one another. Some monitored the enemy's attack direction and sounded the alarm; others quickly maneuvered the boat to evade the deadly attack; and still others drew up their weapons, ready to engage the mutated creatures in a desperate battle. When the octopus's tentacles struck again, Xiao Yi, with his agility and precise judgment, skillfully maneuvered his men to evade them. As for the toxic slime, they used the boat's canvas and planks to create a makeshift shield, shielding themselves from the venomous attack. In each crisis, they fully utilized their ingenuity. Taking advantage of the ocean environment, they lured the octopus's tentacles to get stuck on the reefs; analyzing the attack patterns of the strange fish, finding their weaknesses and counterattacking. With fearless courage and extraordinary wisdom, Xiao Yi and his team repeatedly escaped danger in these perilous situations and continued to move forward firmly towards their goal.

During their long and arduous exploration, they unexpectedly made a startling discovery. Sunlight filtered through the sea, creating fantastical beams of light. Amidst this interplay of light and shadow, they noticed something unusual about the seafloor ahead. A large, abrupt depression had appeared on the once flat sandy bottom. As the boat neared, a mysterious cave, hidden beneath the sea, gradually unfolded before their eyes. The cave's entrance was surrounded by a variety of exotic corals and seaweed, as if a barrier deliberately created by nature. The corals were vibrant and varied in color, some resembling blooming flowers, others stretching branches. The seaweed swayed gently with the current, as if guarding this mysterious place. The cave's edges were jagged, its rocks marked by the marks of age. Mysterious lights shone faintly from within, flickering, as if revealing untold secrets. The water around the cave's entrance was exceptionally turbulent, forming small whirlpools that seemed to prevent them from approaching. They opened their eyes wide, full of curiosity and anticipation, wanting to unveil this mysterious cave hidden deep under the sea and explore the mysteries hidden within.

As they cautiously approached the mysterious cave, they saw a strange glow emanating from it. It wasn't a single hue, but a myriad of brilliant hues interwoven, a dreamlike illusion. Sometimes the light was as intense as a burning flame, illuminating the cavern as bright as day; sometimes it was as faint as the flame of a dying candle, flickering in the darkness, creating an air of mystery. The source of the light was elusive, seemingly seeping from the stone walls deep within the cavern, or perhaps emitted by some mysterious object hidden in the darkness. It refracted and scattered through the cavern's vapor, forming beautiful, elusive streaks of light. Enveloped by this strange glow, they keenly sensed that it held the key to unlocking the mystery of the mutation. Every flicker of the light seemed to convey a cryptic message; every shift in color held the potential to unlock the secret. Their hearts beat faster, their breathing quickened. His eyes were fixed on the light, as if as long as he focused enough, he could penetrate the secret behind the light, find the root cause of the biological mutation, and thus save this ocean world ravaged by mutated creatures.

Before the mysterious cave emitting a strange light, Xiao Yi took a deep breath, calming himself. He then turned and gazed resolutely at the team members behind him. "Everyone, be careful. Follow me closely," Xiao Yi whispered, his voice soft but powerful. The team members nodded, their expressions tense and filled with anticipation. Xiao Yi took the lead, slowly approaching the cave. At the cave's entrance, the current of the water grew more turbulent, as if resisting their entry. Xiao Yi carefully avoided the surging currents and led the team deeper and deeper. The light within the cave grew increasingly strange, sometimes flickering a faint blue, sometimes fading into a mysterious purple, as if transporting them to a maze of light. Their footsteps echoed in the silent cave, each step feeling particularly heavy. Xiao Yi, lighting tool in hand, cautiously surveyed his surroundings. The cave's walls were covered in strange patterns, some resembling ancient runes, others like mysterious maps. As they went deeper, the cave became narrower and narrower, forcing them to slouch and struggle forward. Xiao Yi kept a constant eye on his head and feet, fearing any unknown danger would suddenly approach. The team members followed closely behind Xiao Yi, staying close to each other, as if they could draw more courage and strength from their companions. In this mysterious and unknown cave, every step forward was filled with anxiety and anticipation.

The moment Xiao Yi led the team into the cave, a strong, pungent odor instantly assaulted their nostrils. The scent, a nauseating mixture of decaying seaweed, stale minerals, and some indescribable chemical, was overwhelming. The team members covered their mouths and noses, but the acrid odor seemed to penetrate every pore, drilling straight into their nasal passages. Every breath felt like rough sandpaper rubbing against their throats, excruciatingly uncomfortable. On the cave walls, mysterious runes shimmered. These runes were not arranged in a neat, orderly pattern, but rather in a seemingly random pattern that seemed to follow some ancient law. The runes glowed faintly, some shimmering a faint blue, like will-o'-the-night will-o'-the-wisp; while others emanated an eerie green, like a poisonous miasma. The light waxed and waned, causing the runes' shapes to shift, sometimes clear, sometimes blurred and distorted. A closer look revealed the intricate and delicate lines of the runes, as if meticulously carved by a skilled craftsman. Each rune seemed to contain endless mysteries and power, making people want to decipher the meaning behind them. Surrounded by this pungent smell and mysterious runes, Xiao Yi and his team members felt more and more that this cave was hiding countless unknown secrets and dangers.

The deeper they went into the cave, the more pronounced and intense the pressure became. At first, it was a subtle feeling of oppression, as if an invisible hand were gently pressing down on their shoulders. But as they advanced, the pressure grew heavier. The air seemed thicker, and every breath required immense effort.