A UK man hoping to surprise his girlfriend with a romantic underwater proposal in the Maldives got so nervous he forgot to write his "will you marry me?" message on his dive slate.

The elaborate video, filmed in January this year on a dive in South Atto, shows Simon surprise his girlfriend Marnie in an epic proposal while they were doing a scuba dive.

Writes filmer and friend Richard Stevens: "The plan was to do it during the last dive of the day, but closer to the time of the dive, the more nervous Simon got and he forgot to write the proposal message on the dive slate before the dive!

"Just before we entered the water he slipped me the blank slate and asked me to write the message - I didn't see Simon the whole dive - right until we were close to the end in fact. I slipped him the slate and gave him a nod of encouragement.

"We lured Marnie away with a sighting of a bogus turtle while Simon got into position, and the rest is history!"

Ironically, moments after the proposal a real turtle appears in the video and photobombs the proposal

"We all had quite a laugh back on the boat! The day couldn't have been better as we'd seen plenty of manta rays in the water earlier that day, so everyone was in a great mood!"