Mask out areas without elevation

Good day everyone!

I applied Mask out areas without elevation back in the Back-Geocoding operator while doing Coregistration. But water bodies (specially sea area) is not masked out in the images. DEM used was SRTM 1sec (hgt). I saw posts in this forum saying SRTM 1sec is more useful, but how was it different with the one with ‘hgt’ on it?

My study area is located in Surigao City, Mindanao, Philippines with latitude 9deg27min which is good for SRTM coverage.

It always depends on the DEM you use for masking and which areas are defined zero. This can differ between the datasets, so you can first load them into SNAP (right click > add elevation band) and visually check their quality. Also, the Pixel Information window will show you where they are zero.