What NFL stadiums are near the sea coast?

It really depends on what you mean by "near the sea coast" (within 15 miles). If you are looking for the closest that is to an Ocean, number 5 SoFi is probably the closest at 5 miles from the Pacific.

So here are the remaining contenders:

1) TIAA Bank Field: Jacksonville, Florida is right on the St Johns River which is only 15 miles from the Atlantic Ocean.

2) Hard Rock Stadium: Miami Gardens, Florida is only 7 miles from the Atlantic Ocean.

https://piershare.com/blog/football-by-boat-stadiums-on-or-near-the-water

3) Raymond James Stadium in Tampa is 2 miles from Tampa Bay the Atlantic Ocean (Gulf of Mexico)

4) Levi Stadium in St Clara is about 1 mile from San Fransico Bay.

5) SoFi Stadium is about 5 miles from the Pacific Ocean

https://www.caliper.com/featured-maps/maptitude-nfl-stadium-map.html