The secret at the bottom of Joy of Life Lake was the Forbidden Door. According to the contents of Ye Qingmei's letter to Fan Xian, there was a forbidden door hidden at the bottom of the lake. This door might be a laboratory. There might be modern high-tech equipment inside, such as mobile phones, navigation, computers, and so on. The Forbidden Door involved the birth, aging, sickness, and death of humans, as well as Fan Xian's life and fate. Fan Xian might open this door and enter the hidden door. There might be many terrifying things inside the hidden door, and many truths were hidden. Ye Qingmei's death was related to this secret. Fan Xian might reveal the truth of his mother's death to fight to the death with the Qing Emperor. In short, the secret at the bottom of Joy of Life Lake involved the Forbidden Door, the laboratory, high-tech equipment, Fan Xian's life and fate, and the cause of Ye Qingmei's death and the truth.

The secret at the bottom of Joy of Life Lake was the Forbidden Door. According to the contents of Ye Qingmei's letter to Fan Xian, there was a forbidden door hidden at the bottom of the lake. This door might be a laboratory. There might be modern high-tech equipment inside, such as mobile phones, navigation, computers, and so on. The Forbidden Door involved the birth, aging, sickness, and death of humans, as well as Fan Xian's life and fate. Fan Xian might open this door and enter the hidden door. There might be many terrifying things inside the hidden door, and many truths were hidden. Ye Qingmei's death was related to this secret. Fan Xian might reveal the truth of his mother's death to fight to the death with the Qing Emperor. In short, the secret at the bottom of Joy of Life Lake involved the Forbidden Door, the laboratory, high-tech equipment, Fan Xian's life and fate, and the cause of Ye Qingmei's death and the truth.
The secret at the bottom of Joy of Life Lake was the Forbidden Door. According to the contents of Ye Qingmei's letter to Fan Xian, there was a forbidden door hidden at the bottom of the lake. This door might be a laboratory. There might be modern high-tech equipment inside, such as mobile phones, navigation, computers, and so on. The Forbidden Door involved the birth, aging, sickness, and death of humans, as well as Fan Xian's life and fate, as well as Ye Qingmei's experiment and the truth of the seed. Fan Xian might reveal the truth of his mother's death to fight to the death with the Qing Emperor. In short, the secret at the bottom of Taiping Courtyard's lake might involve Fan Xian's life and fate, as well as the truth of Ye Qingmei's experiments and seeds.
The bottom of Joy of Life's lake was where the Forbidden Door was located. According to the contents of Ye Qingmei's letter to Fan Xian, there was a forbidden door hidden at the bottom of the lake. It might be a laboratory, and there might be modern high-tech equipment inside. Fan Xian might open this door and enter the hidden door. There might be many secrets inside the hidden door.
The bottom of Joy of Life's lake was a place known as the Forbidden Gate, or it could be a temple. According to the description in the novel, there might be some high-tech instruments and scientific literature hidden at the bottom of the lake, as well as letters between Ye Qingmei and the Qing Emperor. The specific details and content could not be found in the search results provided, so there was no definite answer.
The bottom of Joy of Life's lake was where the Forbidden Door was located. According to the contents of Ye Qingmei's letter to Fan Xian, there was a forbidden door hidden at the bottom of the lake. It might be a laboratory, and there might be modern high-tech equipment inside. Fan Xian might open this door and enter the hidden door. There might be many secrets inside the hidden door. The specific details and content were not found in the search results provided.
The bottom of Joy of Life's lake was thought to be a place known as the Forbidden Gate, or it could be a temple. According to the description in the novel, there might be some high-tech instruments and scientific literature hidden at the bottom of the lake, as well as letters between Ye Qingmei and the Qing Emperor. However, the specific details and content were not clearly answered in the search results provided. Therefore, I'm currently unable to determine what exactly is at the bottom of Joy of Life's lake.
The bottom of Joy of Life's lake was known as the Forbidden Gate, and it could also be a temple. According to the descriptions in the novels and dramas, there might be some high-tech instruments, scientific literature, and letters between Ye Qingmei and the Qing Emperor hidden at the bottom of the lake. The specific details and content were not found in the search results provided.
The bottom of Joy of Life's lake was a place called the Forbidden Door. It could be a laboratory or a temple. According to the description in the novel, high-tech instruments, scientific literature, and letters between Ye Qingmei and the Qing Emperor might be hidden at the bottom of the lake. The specific details and content were not found in the search results provided.
The bottom of Joy of Life's lake was thought to be a place known as the Forbidden Gate, or it could be a temple. According to the description in the novel, there might be some high-tech instruments and scientific literature hidden at the bottom of the lake, as well as letters between Ye Qingmei and the Qing Emperor. Fan Xian might open this door and enter the hidden door. There might be many secrets inside the hidden door.
The bottom of Joy of Life's lake was known as the Forbidden Gate, and it could also be a temple. According to the descriptions in the novels and dramas, there might be some high-tech instruments, scientific literature, and letters between Ye Qingmei and the Qing Emperor hidden at the bottom of the lake. However, the specific details and content were not found in the search results provided. Therefore, it was still uncertain what exactly was at the bottom of Joy of Life's lake.