Two White Boats
I suppose you could say this is the reverse of 'colour popping'.
I have punched a hole in the colour version to reveal a monochrome version beneath.
To be more precise:
I loaded the image into GIMP and duplicated the layer twice.
Lowest layer desaturated and curves used to create a bright image of the boats.
Middle layer desaturated and curves used to give an overall range of contrast
Top layer: applied Gaussian blur with a radius of 400, then auto colour enhance, then repeat Gaussian blur with radius of 120, finally set combine mode to 'colour'and adjusted opacity until satisfied.
Then merged down the top layer onto the middle one and added a (white) layer mask. Used black to paint the mask where the boats were, which allowed the bottom brightest monochrome layer to show through.
Flattened the image and applied a final sharpen (unsharp mask).