See data-raw/oisst.R in the source repository. The file was avhrr-only-v2.20170729.nc, its extent -180, 180, -90, 90 with dimensions 1440x720 in the usual raster configuration.
A data frame of sst values created from OISST data.
oisst
#> # A tibble: 1,036,800 × 1
#> sst
#> <dbl>
#> 1 -1.28
#> 2 -1.28
#> 3 -1.28
#> 4 -1.28
#> 5 -1.28
#> 6 -1.28
#> 7 -1.28
#> 8 -1.28
#> 9 -1.28
#> 10 -1.28
#> # ℹ 1,036,790 more rows