Mark Hardaker, 40, was celebrating his wife's 40th birthday at the Mana Island Resort and Spa when he decided to take a fishing tour. He never came back.

Fijian West police say Mr Hardaker, from Toongabbie in Sydney's west, was on a boat with three other men when another vessel slammed into them at a high speed on Thursday.

Fairfax Media understands the boat that crashed into Mr Hardaker's boat was driven by a local operator and had been carrying too many people at the time.

Mr Hardaker's widow, Vanessa, and their children flew home the following day.

Mr Hardaker's sister-in-law described him as a doting father who loved his wife.

“Mark is the most amazing thoughtful selfless person I will ever know in my life,” Alana Rice wrote on Facebook.

“He adored my sister and forver [sic] loved his children,” she said.

“My sister was there for her 40th bday celebrations tommow [sic] and is now flying home alone with 3 children.”

Mr Hardaker's step-mother Gay Bookallil said she was devastated by the loss.

“We are absolutely devastated and cannot begin to express how sorry we are for our much loved daughter-I-law Vanessa and grandchildren Georgia, Sam and Jake,” she posted online.

Fijian West police spokesman Naina Ragigia said the other people on board Mr Hardaker's boat had received treatment for a number of injuries.

He also said the company operating the vessel had never been involved in an accident before.

A Department of Foreign Affairs and Trade spokeswoman confirmed the death and were helping to organise for Mr Hardaker's body to be flown home.