Shortly after 9pm on Thursday (July 8), police received a report of a small number of packages in the sea off the coast of Seaford.
The packages were tested, and were found to contain Class A drugs.
Additional packages have since been recovered, police said on Sunday (July 11), taking the total estimated street value to around £2 million, and officers continue to maintain a presence in the area to identify any further packages.
Members of the public are urged to dial 999 immediately if they come across any suspect packages in the area.
On Sunday, a spokesman for Sussex Police said: “Three men were arrested in the area on Thursday night on suspicion of improper importation of goods – controlled drug of Class A.
“A man and a woman were also arrested on suspicion of being concerned in the fraudulent evasion of a prohibition on the importation of a Class A drug.
“They have all been released on conditional bail while enquiries continue.
“Anyone who saw any suspicious behaviour in the vicinity on Thursday evening, or who may have any other information relating to the matter is asked to contact police online or by calling 101 quoting serial 1518 of 08/07.
“Alternatively, you can contact the independent charity Crimestoppers anonymously on 0800 555 111.”