The funding was initially announced in early January with the first lot of loans totalling $4.75 million received by February 8.
To date Nautilus has received loans totalling $9.65 million, for which the company has issued the lender a total of 41,451,888 share purchase warrants.
Each warrant entitles the lender to purchase one common Nautilus share at a price of $C0.205 for a period of five years from the date of issuance.
The funds will help Nautilus with its immediate working capital requirements and facilitate payments required to continue the development of its seafloor production system to be utilised at Solwara 1.
The loans bear interest at 8% per annum, payable bi-annually in arrears with a one-year maturity date. Nautilus will be entitled to pre-pay each loan prior to maturity by paying 108% of the outstanding principal of the loan plus accrued and unpaid interest.
Providing the funding is a recently incorporated private company in the British Virgin Islands, jointly owned by subsidiaries of USM Holdings Ltd and MB Holding Company LLC.
Both are major shareholders of Nautilus, so the lender is a designated "related party" and the loans a "related party transaction" under the relevant Canadian securities regulation.
The Solwara 1 project will require up to $350 million in order to complete development.
According to the preliminary economic assessment released February 27, based on a third quarter 2019 first production date, the project will deliver about 20,000 tonnes of copper and 29,000 ounces of gold when at steady state production of roughly 3200 tonnes per day.
Cash costs will be $1.36/lb copper for the entire deposit and $0.80/lb when at steady state.
The company, however, forecasts first production for the second quarter of 2019.
It initially reported last September that the project required substantial additional funding, and subsequently failed three funding deadlines by December.
Former chairman Russel Debney stood down following the third unmet deadline.
Nautilus was granted its first mining lease in January 2011 for Solwara 1 and the environmental permit for the project was awarded in December 2009.
The Solwara 1 deposit, which is on the seafloor at a water depth of about 1600m, contains a copper grade of about 7%. That compares with land-based copper mines, where the copper grade today averages 0.6%.
In addition, gold grades of more than 20 grams per tonne have been recorded in some intercepts at Solwara 1 and the average grade is about 6gpt.