The two Swedes, 24-year-old Christian Karlström, and a 25-year-old woman named only as Catherine, were last heard from on Saturday when they left Morea, north of Tahiti, and were sailing towards New Zealand, according to the newspaper Aftonbladet.
Their parents have informed the foreign ministry of their fears for the safety of the pair.
“The embassy in Canberra is trying to get in contact with them, with help of their contacts in Samoa,” André Mkandawire at the foreign ministry confirmed to the newspaper.
Christian Karlström left his home of Östersund in northern Sweden in April on a year-long sailing trip. He flew to Panama with a 22-year-old friend from Sweden and met up with a Belgian friend and his 12 metre yacht.
They set sail for the South Pacific shortly after arrival in Panama and have been keeping regular phone contact with their families in Sweden since.
Catherine joined the party when they met in the Galapagos islands in June.
But since telephone calls to their respective parents on Saturday nothing has been heard from them.
During the phone call Christian Karlsson told his parents that his friend had switched to another boat. He has since been located safe in Roratonga and has confirmed that he has also been unable to contact either Christian or Catherine.
The parents remain hopeful that the pair have found shelter on one of the islands in the area.
“Of course we are worried, but we think that they are on some island. She said that they were going to the Cook Islands,” Catherine’s father told the newspaper.
The tsunami struck the Samoan islands and Tonga on Tuesday causing widespread destruction and a death toll which currently stands at 149.
The 4.5 metre high tsunami was generated by an 8.3 magnitude earthquake which struck the area at 6.48pm Swedish time.