United Kingdom, March 15 -- Metallica frontman James Hetfield proposed to his longtime girlfriend Adriana Gillett while underwater snorkelling with sharks.

The 62-year-old thrash metal legend took his 46-year-old partner diving with whale sharks on Friday the 13th (13.03.26) - also her birthday - in the most rock 'n' roll proposal ever.

He held up a sign underwater reading: "Adriana Gillett, will you marry me?" The Instagram snap was captioned: "She said yes!"

Offering further insight into the unique proposal, Adriana shared on her own account: "The BEST birthday trip surprise. Swimming with whale sharks on Friday the 13th with the most unique, special, and romantic proposal a Pisces could ever imagine. In a sea full of fish, we caught...