There is some good news for international ships, which are flying either a Republic of Korean flag (South Korea) or a Chinese five-star flag, sailing between China and South Korea.
Taking into account the difficulties found in conducting a safe and efficient ballast water exchange in the waters between China and South Korea, the maritime safety administration of China has issued a notice (Marine anti-pollution Decree  No. 661), exempting such ships from conducting ballast water exchange in accordance with Ballast water management (BWM) convention regulation B-4.1 and D-1.
There are, however, some points to note:
The decision for not conducting a ballast water exchange should be clearly recorded in the ballast water record book detailing the reasons.
It should also be noted that this exemption is not applicable to ships which are required to meet the D-2 standards of the BWM convention as per regulation B-3. Therefore, if a ship is required to have an operational ballast water treatment plant, it should continue to treat its ballast water as per the D-2 standard.
It is interesting to note that the exemption ceases on 7 September 2024. This is because, by this date, almost of all the merchant fleet will have moved to meeting the requirements of regulation D-2 of the BWM convention and there would be no need for conducting ballast water exchanges unless in exceptional circumstances.
Source: Maritime Shipping News