Please note that if you extract this archive on Windows, the directories SEASMR20_001 and seasmr20_001 in seasat/retired/L2/smmr/ will get merged. I've had this issue with my copy and since separated them again.

The hash of the extracted files is as follows:
find seasat -type f -exec md5sum {} \; | sort -k 2 | md5sum
5f56cabc7501dfeb0171b15ef5ed5c04  -

This copy was downloaded from ftp://podaac.jpl.nasa.gov/allData/seasat/ on 27/01/2017.