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
Environment
MC 18w30b Server Hosted on an Intel i7-4790K 4.00 GHz with 4GB 1866 MHz DDR4 RAM , SSD(Hosted by https://www.minecraft-hosting.pro).
Server is running on Java 8
Playing on a 2017 iMac running macOS Mojave, 4.2GHz Intel Core i7 with 24 GB 2400 MHz DDR4 RAM and a Radeon Pro 575 with 4096 MB.
Computer is on Java 8
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.