On my1983 H-3 I have the same indents in the main cabin, the head, outside the head and in the v- birth.
The main cabin had thin teak plywood and a diamond Treadmaster type product in all the other areas. The plywood was beyond repair and the diamond flooring just plain gross. I carefully removed the old flooring to be used as patterns. I used a straight edge razor, paint thinner and then goof off to remove the old glue. (Be careful using Goof Off the fumes are strong and you'll need lots of venting)
I made up replacement sections out of teak colored solid vinyl planking sold in Home Depot. The vinyl planking glues to itself by pulling off a paper cover and not to the sole of the boat. I assembled rectangular sections and then used a straight edge and razor knife to cut the section to the shapes using a belt sander where necessary to clean up the radius edges. I was careful to assure that the strips of planking ran fore/aft.
I made up all the sections at home on the basement floor and then installed them in the boat. Getting the section for main cabin floor, which was one large piece, up the ladder in the boat yard and then through the main hatchway was very tricky. If I ever do it again I may make it in 2 sections. I used daubs of silicone to hold the flooring in place.
It took 2 boxes of flooring to do all the sections. The main cabin floor took a little less than 1 box with the other sections needing a second box with quite a few pieces left over
Not quite as classy as real teak but indestructible and impervious to sand, grease, diesel, water……….