Freedive world champion William Trubridge's parents say they are "naturally nervous" in anticipation of their son's 102-metre plunge into the oceans' deepest blue hole.

Tomorrow's Steinlager Live Dive is the purest form of freediving - he is not allowed to touch the rope or use any form of propulsion assistance.

His passion for being underwater stemmed from a bond he formed with the ocean while a toddler as his parents and brother, Sam, sailed from England.

Father and Hawke's Bay designer, David Trubridge and mother, Linda, attended his latest dive in the Bahamas, but tomorrow they will be watching from the edge of their seat in Auckland's TVNZ studio.

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"We are naturally nervous for him, mostly because of how all this attention he is getting makes it harder for him to remain as totally relaxed as he has to be in order to succeed," his father said.

"But he is incredibly level-headed and if anyone can do it he can."

His father said the most difficult thing was that each time his son achieved a new record it made the next attempt more difficult.

Tune in to TVNZ Breakfast to see Trubridge's attempt at 7.40am tomorrow. For more information, visit williamtrubridge.com.