If you are sprint swimming and you get in a boat your view is centered under the boat like you were still 1 block tall.
This applies to all views. See video down below for more reference.
Occurs on both single player and multiplayer
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Thank you for your report!
We're actually already tracking this issue in MC-100195, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.