This one is relatively straightforward. Swim the Cook Strait and obtain free Interislander crossings for life after verifying your swim. A pretty good deal if you ask me!
I suggest swimming South to North and doing it in Summer.
More info at NZOWSA
https://www.nzowsa.nz/cook-strait
Let me see if this might be achievable to 99.9% of the population.
I'll be right back.