Data obtained with:
mkdir raw cd raw wget --no-parent -r -l inf --wait 5 --random-wait 'https://www.ncei.noaa.gov/data/sea-surface-temperature-optimum-interpolation/v2.1/access/avhrr/'
This tries to be polite with the NOAA: enforces a wait time always and in addition randomizes it to make it variably longer. No boundary on depth of folder recursion. There are a lot of files. Doing it this way will take several days in real time (much less in actual transfer time of course).
Update a subfolder: wget --no-parent -r -l inf --wait 5 --random-wait 'https://www.ncei.noaa.gov/data/sea-surface-temperature-optimum-interpolation/v2.1/access/avhrr/202402'
and remove preliminaries