Going in water makes the diving noise
MC-126863
Sounds made with water in spectator mode
Resolved
Fixed
4
Confirmed
Minecraft 18w10b, Minecraft 18w11a, Minecraft 18w15a, Minecraft 18w20c
Minecraft 18w21a
Retrieved
Just want to chime in that this report is still relevant today. 18w15a also has this problem.
But another reason for my comment: this seems to be a re-occurring bug because MC-46470 involved the same symptom (yet that one got resolved).