St Patrick's College students will cover hundreds of kilometres without leaving the safety of their school on Thursday.
The year 12 students will participate in the annual Lap it Up event, which raises money for the Edmund Rice Foundation and four charities supported by the four school houses.
Lap it Up is a whole grade cohort event, with all students participating in a 24-hour triathlon, with students signing up to participate in particular hours.
College captain Sasha Massey said for each hour, there needed to be at least two students competing for each leg.
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It is entirely student run and is organised through student committee factions, who are responsible for particular elements.
"We encourage our peers to sign up to be part of the organising committee and this year we've had the biggest sign-up rates for the event," Miss Massey said.
To compete, individuals can sign up to do one or more of the triathlon legs to ensure all the 24-hour slots are covered.
Total distances will be recorded with "record totals" being one target students can aim for during the event.
Lap it Up committee member Maddie Johnston said it was a bit of a rite of passage among grade 12 students at St Patrick's College.
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"You see the grade 12s above you participate so it's great when you finally get there and can organise and participate yourself," she said.
"It's the last whole grade thing we do before exams and end-of-year hits."
All year 12s will meet at the event for "everybody hour" on Thursday at the gym, where students are taught about the Edmund Rice Sinon School in Arusha, Tanzania.
The Sinon School is St Patrick's College's sister school, with funds raised from the event sent to support it.
Other charities to benefit from the event this year are the Edmund Rice Camps, the LGH Children's Ward, the Holman Clinic and The Smith Family.
Lap it Up will be held from 9am Thursday and will finish at 9am on Friday.
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