Dosch HDRI: Seascapes Vol.2 contains 20 HDRIs of skies with water surfaces. 

The resolution of the Spherical Map HDRIs is 17,596 x 8,798 pixel.

High Dynamic Range Images (HDRI) are a perfect solution for the realistic lighting and environmental imaging of 3D scenes.

HDRIs are 360-degree panoramas for all kinds of renderings in the areas  of product visualization, CGI, real-time rendering, which are  illuminated with the help of IBL (Image Base Lighting).
Outstanding reflections, impressive lighting moods and real-looking environments are the result.

And each HDR image is provided in the industry standard .HDR. So they are useable in most rendering applications.