I've had quite a few surfing and kitesurfing.
Probably 4 or 5 times kiting come over the back of a swell or wave and seen a shark cruising along-invariably it was more freaked to see me than I was it and they've taken off as soon as I've popped over the wave.
Surfing saw a HUGE shark at The Bower when I was a kid-a huge fin popped up in front of a few mates and I when paddling across the channel to Manly-we freaked and paddle up the rocks.
In Indo I've had numerous reef shark encounters-they seem pretty harmless, so far

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Once out trawling for marlin off Port Stephens we came across a whale carcass about 5 or 6 miles out and a HUGE white, between 15-20 feet (and more at the upper end) was feeding on the carcass-the shark was so big, it's girth was like a VW bug.
Caught, tagged and released my share of h/heads.
Found the body of a fisherman once (he was washed off the rocks at N Head-Syd. Harbour) when going fishing through the Heads and there was a group of small h/heads feeding and circling his body.
Lived on the headland at Palm Beach in Sydney and one day saw a group of 3 surfers oblivious to the fact that there was a sizeable shark about 10m away thrashing away at a bait ball, funny thing was another group about 50m away did see it and freaked and paddle in and run up the beach to warn the oblivious surfers, who then freaked and cartoon paddled up the beach.
Seen heaps of Wobbys etc. when diving.
Was out paddle surfing about 2 weeks ago and 60 Minutes was down filming Andy Lindrop at Palmy having one of his first surfs back after he was attacked at Avalon earlier this year. We shared a few waves and hooted him in to a couple.
So far I've escaped being bitten, to the chagrin of some...