Sir John will be part of 75-strong team raising money for charity
Seventy five people – including the Isle of Man's Lieutenant Governor - are preparing themselves for a sleepover on Snaefell.
It's part of a fundraising initiative by Manx charity Breast Cancer Now.
The event will take place on 7 May and will see those taking part pledging to raise a minimum of £300 each in sponsorship and donations.
Sir John Lorimer will be joined for a night under the stars by his wife Lady Philippa, and says they're both excited:
RAF veteran praises 87-year-old for 'fantastic effort' as duo conquer Ben Nevis
MLC to quiz colleagues on legislative priorities
Government focussing on 'maximising use' of Liverpool ferry terminal
Douglas Council brings in new charges for crematorium