landscape - Capturing vibrant colors on a bright, sunny day

Recently I was on a vacation trip at Phi Phi Island with my Nikon D5300 and a simplistic 18-55 NIKKOR kit lens. I was sailing on a cruise. It was a bright, in fact very bright, sun outside. On a boat, mounting on tripod would make no sense since the platform was swaying heavily. So, HDR or AEB shots were impossible to take. Precisely, I couldn't take multiple shots of the same frame in different exposures due to lateral and forward motion of the boat. Moreover, to avoid blur, I was forced to use a faster shutter speed and set the ISO a bit higher to compensate accordingly. To capture the details in highlight, I underexposed by -1/3 or -2/3. However, in spite of all those fantastic calculations, a large fraction of the images taken were somewhat washed out / brightened. Particularly, I didn't like the white glare.

In GIMP, if I apply Tools => Color Tools => Levels => Auto, it improves the picture to some perceivable extent. Below I share on of the worst shots and the edited version of the same. Relevant EXIF of the original capture is: [ISO => 400, F11, 1/320 seconds, -1/3 EV]

Original

Edited

What could I do to capture (1) vibrant colors (2) in a bright landscape (3) while in motion (4) straight-out-of-camera?

All four of the points above are important for this question. My initial research on the same reveals:

1. Underexposure: May be I could underexpose a little more, possibly all the down to -1 stop. I am afraid that would ruin the images in the other way.


2. Better lens: I am not sure which lens though keeping in mind that I am on a crop-sensor camera and on Nikon line. Any suggestion?


3. Shoot in RAW: Would that help in post-processing? Please note that, this option still conflicts with clause #4 (SOOC)



4. White balance: It was set to AUTO. Any advise on that?


5. Camera mode: Probably, there's some LANDSCAPE mode. How well does it perform? I never tried that since I presumed that it takes some camera controls beyond my control.


6. Polarizer: I don't have one. Does it worth investing on it to improve images under similar condition?


7. UV filter: I have got one cheap one mounted on my lens. It gives me the "sense of safety" of protecting my lens. Haven't seen any improvement in the image quality though.