Two women have been arrested after being found with suspected heroin thought to be worth around £40,000.
Police Scotland say a 42 year-old and a 35 year-old were detained by officers as they tried to leave the ferry from Aberdeen.
Both remain in police custody and a report will be sent to the procurator fiscal in Lerwick.
Chief Inspector Lindsay Tulloch said: “As a community we need to reduce the market for controlled drugs in Shetland by supporting and helping those affected by, and addicted to controlled substances to seek recovery services.
“I hope todays arrests will signal to others the risk involved in carrying drugs to Shetland. As always, I would ask anyone with information of drugs misuse to contact us at Lerwick Police Station.”