To replicate:
Start flying with elytra
Go in water
Go backwards
You can also fly and swim and use a fire work rocket to boost your self while under water
Environment
Windows 10 (64 bit), i7 Core 7700HQ 2.8Ghz, 16g RAM
Java (build 1.8.0_171-b11)
MC-131189
Flying upside down in water
Resolved
Duplicate
0
Duplicate of MC-125436 and MC-97190