In July, an estimated 14kgs of cocaine washed up on beaches in Vava'u.
Tongan police seized the haul and an ongoing investigation has seen 21 people charged so far including three foreigners.
At the end of August, Acting Deputy Commissioner of Tonga Police Halatoa Taufa told Matangi Tonga the recent arrests included a 49-year-old man and his 23-year-old wife from Ta'anea, Vava'u on August 23.
The couple are in police custody charged with engaging with others in the supply of illicit drugs.
Previously, 19 people had been arrested and charged in relation to the cocaine seizure, which is estimated to have a street value of over $US2.2 million.
Of the 21 arrested so far, three were in Tongatapu and the rest in Vava'u.
But Tonga is far from the first Pacific country to have to deal with drugs turning up on their shores.
In 2019 authorities in French Polynesia stumbled on a massive haul of cocaine aboard a yacht, which had only come into dock because it had developed engine problems.
Cocaine has also been seized by authorities in Fiji in 2018 and also in 2018 a multi-national sting operation saw the seizure of cocaine aboard a yacht originating in South America.
The unique geography of the Pacific region creates a significant challenge for drug enforcement, according to the Pacific Islands Chiefs of Police network.
Its executive director Glyn Rowland said the sheer size of the Pacific Ocean makes it difficult to detect the movement of illegal drugs, which can be easily concealed and transported in small vessels.
Mr Rowland said the Pacific is a transit route from South America to the lucrative drug markets of Australia, and to a lesser extent New Zealand.
He believes the cocaine that washed ashore in Vava'u could have come from this supply chain.
Mr Rowland also said the Covid-19 pandemic has had an impact on drug routes in the Pacific.
"Certainly, for our young people, unemployment and poverty is a challenge right now because of the pandemic and that makes them quite vulnerable to recruitment into organised crime gangs and facilitating drug movements," Mr Rowland said.
He said the Chiefs of Police are mindful of what is going on in the region and there needs to be a concentrated effort to address the issues.
He said this has led to the establishment of the Pacific Transnational Crime Network.
"The network is made up of 20 countries that are working together, sharing information about drug trafficking, money laundering and organised crime gangs," said Rowland.
"We are also working together with our partners like the immigration and customs to address some of these issues."
Glyn Rowland said drugs destroy the real fabric of family life.
"The social harm that drugs can cause is pretty immense at every level of society.
"It then leads to the membership of organised crime gangs, that can lead to the gang lifestyle and then that can lead into the mistreatment of women and children.
"We also know that drugs can impact domestic policing, so dishonesty offending such as burglary and acts of violence, so it really does damage one's way of life," Rowland said.
