Deep Sea for All: My Submarine Has Unlimited Upgrades

Survival for all] + [Doomsday] + [Vehicle Upgrade] + [Golden Entry] + [Decisive Killing] + [Behemoth] + [Cthulhu] + [Invincible Flow] + [Multiple Female Hosts] + [Submarines Only Accept Women] Upon waking up, tens of billions of people around the world were thrown into the endless deep sea, each with an old submarine. There are storms and thunder on the sea surface, and there are terrifying monsters in the deep sea. Lack of oxygen, water pressure, and lack of resources are the countdown to death! When others sold their dignity for a mouthful of survival supplies, Xia Hai looked at his submarine panel and smiled. [Fuel tank] + [Unlimited] = Unlimited fuel! [Shell] + [Deep Diving] = Ignore the water pressure of 10,000 meters! [Sonar] + [Omniscient] = All information is invisible! [Submarine] + [Space Folding] = Moving Castle, with storage rooms, swimming pools, villas, and arsenals all available! [Window] + [One-way transparent] = It looks like an iron plate from the outside, but it looks like a panoramic sunroof from the inside, giving you a sense of security! While others were shivering in the shallow sea driving leaky "iron cans", Natsumi was already driving his [Mobile Poseidon] in the 10,000-meter trench, holding the tentacles of the Cthulhu beast with a robotic arm, thinking about whether to eat teppanyaki or sashimi tonight. Every time a vehicle upgrades to a level, it can obtain an extremely powerful "top-level entry". This entry is mandatory at the rule level and can be attached to any part of the vehicle to give it heaven-defying properties.