2. Wet and dry methods

In a dry environment, frogmen breathe normal-pressure air inside the transport craft, maintaining their body temperature and combat effectiveness. Frogmen are only exposed to water when entering and exiting the craft and conducting underwater operations. Therefore, since the 1980s, several countries have begun developing dry frogman transport craft. The US ASDS uses a dry design, with the frogmen's space divided into two compartments: the frogman accommodation compartment and the frogman access compartment. During long-distance transport, frogmen remain in a dry environment, transitioning from the access compartment to a wet environment only when carrying out missions. Two to three frogmen can enter and exit at a time.

3. Continuously optimize the system

Higher speeds mean better maneuverability, allowing frogmen to quickly maneuver to the designated sea area, reducing transport time and exposure, and escaping enemy threats in emergencies. Currently, the world's leading small frogman carriers have achieved a maximum speed of 5-6 knots, with a cruising speed of approximately 3-3.5 knots. Frogman transport boats have a maximum speed of 8-10 knots and a cruising speed of approximately 6 knots. However, for wet-type frogman transport platforms, frogmen cannot withstand excessive speeds, so excessive speed is not an option. A balance must be found between the two. Currently, small frogman carriers primarily employ the addition of baffles or partial body wrapping to increase speed while reducing the impact of water currents on the human body. Wet-type frogman transport boats are typically designed with opening and closing hatches, which are closed during high-speed underwater operation to reduce impact and maintain the frogman's body temperature.

If a small frogman carrier is directly deployed from a submarine, its combat radius is only 1.5 to 3 nautical miles, forcing the submarine to move very close to it, greatly increasing the probability of detection. Therefore, frogman delivery platforms currently require longer range and a larger combat radius, but this also needs to be considered in combination with the frogman's underwater endurance and energy consumption ratio. A balance needs to be found between the two to achieve a more optimized system.

4. Multifunctional modular development

Originally, the primary or sole function of underwater mobile platforms for frogmen was to transport frogmen. In recent years, with the need to address multi-mode threats and technological advancements, there has been a gradual trend from single-mode underwater transport to combined surface and underwater transport, from transport-only platforms to a combination of transport and attack, and from manned combat platforms to a hybrid of manned and unmanned platforms.

Furthermore, while frogman transport platforms are performing special operations missions, they are also increasingly being equipped for diverse missions, such as underwater rescue and underwater construction. Countries are developing their own surface/underwater hybrid frogman transport vessels. For example, the US MRCC (Multi-Role Combat Craft) can handle multiple functions, including surface reconnaissance, littoral combat, underwater infiltration and evacuation, non-combat retreat, intelligent reconnaissance, and information management. The US Hyper-sub boat is capable of both underwater rescue and mine warfare operations. Italy's CE2F/X100-T SDV platform, in addition to its frogman transport capabilities, can also carry five miniature torpedoes for underwater special operations.

From the current situation, the United States' underwater combat system is the most advanced. For example, the U.S. Navy SEALs, each of them has very strong combat capabilities, can adapt to various tasks, and also master languages ​​​​of various countries, can drive various vehicles and so on.

So the country is now trying to cultivate this type of talent. If you were to face them right now, you'd have virtually no chance of winning. So you need to redouble your training. These three months will be the most unforgettable moments of your lives. Now, let's move on to the first step—holding your breath underwater. Go in first, and I'll see how long you can hold your breath."

Everyone took off their clothes and went into the water without saying anything after hearing the order. The water temperature in the morning was not bad, it was warm, so they didn't have to worry about the water being cold.

Those who could stand here were arguably the best in the army, their abilities were all top-notch, and their lung capacity was undoubtedly impressive. At five minutes in, someone emerged, followed by a second, a third, and so on. Five minutes later, only the Marines and Xiang Jingtian were left. There was nothing much to say about the Marines; dealing with water naturally required specialized training, and Xiang Jingtian had simply spent one point on Diving Mastery. This skill allowed one to ignore water pressure and hold their breath for an hour within 50 meters underwater. The underwater activity time could reach 30 minutes, with the limit reduced by half after 50 meters. When the time was up, simply surface and inhale to refresh. (This skill was stackable.)

Wow, this skill is simply amazing. If I keep buying this skill, I will have to dive into the Mariana Trench. But it’s just a thought. I don’t know how many points it will cost to learn so many skills. Just learn enough.

Fifteen minutes later, there was still no movement on the surface. The blue whale panicked and went over to check the situation. At this time, a head appeared on the surface of the water. This person was a Marine. Seeing someone coming up, the blue whale was relieved and asked, "Why are you alone? Where is the other person?"

The Marine brother gasped and said, "He's still down there. I just saw him."

Blue Whale said: "Well, let's wait and see. If it doesn't get up in five minutes, I'll have to go down and take a look."

So after another five minutes, Xiang Jingtian saw that there was no one around, so he simply went up. When he came out of the water, he met a blue whale that was about to dive in. The blue whale saw him and said, "If you hadn't gotten up, I would have thought you were dead. I was just about to go in to check the situation."

Xiang Jingtian said: "I saw that they all went up, and one person came up because he was bored."

Everyone who heard this really wanted to beat him up. What do you mean you came up because you were bored? It took you a full twenty minutes. Are you possessed by a turtle? I really want to open it up and see if this is a human or a fish. How could he last so long in the water?