Rendered by me.
Rendered in Blender using Cycles Render Engine. Imported through Mineways,with a simple Mix Shader of Glass and Transparent BSDFs for the stained glasses, and either Principled or Diffuse BSDFs for the rest. Just a single Sun Lamp and light background for lighting. Vignette based on various tutorials on Youtube. Total Render Time ~4 hours, for 63 frames.

The main body and saddle was created mostly through worldedit, with some help from voxelsniper. The claws and dock were originally sculpted in Blender 2.79 and imported back into Minecraft through Binvox. The spikes on the back are part of the /cs build spike command and the head was mostly hand-built symmetrically and then rotated.

I tried a new coloring method than usual, where I "masked" each layer and shaded it all monochrome, before replacing each "mask" with a mixture of colors.

(I also later shaded the face.)
I am aware that as it has no wings, it should be classified as a drake or wyrm instead of a dragon, but wings wouldn't really suit an aquatic dragon anyway.

The whole build stands from void level to just a few blocks from max height and is over 200 blocks long.