Sometimes, dismounting a boat on the open ocean will cause the boat to dip below the water. Mounting the boat in this state will result in the player being submerged, but oddly enough without the air meter. The boat is also very jittery when being ridden, but this was difficult to get a screenshot of.
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However, this issue has been closed as a Duplicate of MC-126944 / MC-126950.
It has been linked to this report. If you have additional information, please add it to the duplicated report.
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