diff --git a/pygmt/helpers/caching.py b/pygmt/helpers/caching.py
index 44d9f6f05d1..7bf292a2003 100644
--- a/pygmt/helpers/caching.py
+++ b/pygmt/helpers/caching.py
@@ -9,89 +9,75 @@ def cache_data():
     """
     Download GMT remote data files used in PyGMT tests and docs to cache folder.
     """
-    # List of datasets to download
+    # List of data files to download.
     datasets = [
-        # Earth relief grids
+        # List of GMT remote datasets.
+        "@earth_age_01d_g",
+        "@earth_day_01d_p",
+        "@earth_faa_01d_g",
         "@earth_gebco_01d_g",
         "@earth_gebcosi_01d_g",
         "@earth_gebcosi_15m_p",
-        "@earth_relief_01d_p",
-        "@earth_relief_01d_g",
-        "@earth_relief_30m_p",
-        "@earth_relief_30m_g",
-        "@earth_relief_10m_p",
-        "@earth_relief_10m_g",
-        "@earth_relief_05m_p",
-        "@earth_relief_05m_g",
-        "@earth_synbath_01d_g",
-        # List of tiles of 03s srtm data.
-        # Names like @N35E135.earth_relief_03s_g.nc are for internal use only.
-        # The naming scheme may change. DO NOT USE IT IN YOUR SCRIPTS.
-        "@N30W120.earth_relief_15s_p.nc",
-        "@N35E135.earth_relief_03s_g.nc",
-        "@N37W120.earth_relief_03s_g.nc",
-        "@N00W090.earth_relief_03m_p.nc",
-        "@N00E135.earth_relief_30s_g.nc",
-        "@N00W010.earth_relief_15s_p.nc",  # Specific grid for 15s test
-        "@N04W010.earth_relief_03s_g.nc",  # Specific grid for 03s test
-        # Earth synbath relief grid
-        "@S15W105.earth_synbath_30s_p.nc",
-        # Earth seafloor age grids
-        "@earth_age_01d_g",
-        "@N00W030.earth_age_01m_g.nc",  # Specific grid for 01m test
-        # Earth geoid grids
         "@earth_geoid_01d_g",
-        "@N00W030.earth_geoid_01m_g.nc",  # Specific grid for 01m test
-        # Earth magnetic anomaly grids
         "@earth_mag_01d_g",
-        "@S30W060.earth_mag_02m_p.nc",  # Specific grid for 02m test
         "@earth_mag4km_01d_g",
-        "@S30W120.earth_mag4km_02m_p.nc",  # Specific grid for 02m test
-        # Earth mask grid
         "@earth_mask_01d_g",
-        # Earth free-air anomaly grids
-        "@earth_faa_01d_g",
-        "@N00W030.earth_faa_01m_p.nc",  # Specific grid for 01m test
-        # Earth vertical gravity gradient grids
+        "@earth_relief_01d_g",
+        "@earth_relief_01d_p",
+        "@earth_relief_10m_g",
+        "@earth_relief_10m_p",
+        "@earth_relief_30m_g",
+        "@earth_relief_30m_p",
+        "@earth_relief_05m_g",
+        "@earth_relief_05m_p",
+        "@earth_synbath_01d_g",
         "@earth_vgg_01d_g",
-        "@N00W030.earth_vgg_01m_p.nc",  # Specific grid for 01m test
-        # Earth WDMAM grids
         "@earth_wdmam_01d_g",
-        "@S90E000.earth_wdmam_03m_g.nc",  # Specific grid for 03m test
-        # Earth day/night images
-        "@earth_day_01d_p",
-        # Mars relief grids
         "@mars_relief_01d_g",
-        "@N00W030.mars_relief_01m_g.nc",  # Specific grid for 01m tes
-        # Mercury relief grids
         "@mercury_relief_01d_g",
-        "@N00W030.mercury_relief_01m_p.nc",  # Specific grid for 01m test
-        # Moon relief grids
         "@moon_relief_01d_g",
-        "@N00W030.moon_relief_01m_p.nc",  # Specific grid for 01m test
-        # Pluto relief grids
         "@pluto_relief_01d_g",
-        "@N00W030.pluto_relief_01m_p.nc",  # Specific grid for 01m test
-        # Venus relief grids
         "@venus_relief_01d_g",
-        "@N00W030.venus_relief_01m_g.nc",  # Specific grid for 01m test
-        # Other cache files
-        "@capitals.gmt",
-        "@circuit.png",
-        "@earth_relief_20m_holes.grd",
+        # List of tiled remote datasets.
+        # Names like @N35E135.earth_relief_03s_g.nc are for internal use only.
+        # The naming scheme may change. DO NOT USE IT IN YOUR SCRIPTS.
+        "@N00W030.earth_age_01m_g.nc",
+        "@N00W030.earth_faa_01m_p.nc",
+        "@N00W030.earth_geoid_01m_g.nc",
+        "@S30W060.earth_mag_02m_p.nc",
+        "@S30W120.earth_mag4km_02m_p.nc",
+        "@N00W090.earth_relief_03m_p.nc",
+        "@N00E135.earth_relief_30s_g.nc",
+        "@N00W010.earth_relief_15s_p.nc",
+        "@N30W120.earth_relief_15s_p.nc",
+        "@N04W010.earth_relief_03s_g.nc",
+        "@N35E135.earth_relief_03s_g.nc",
+        "@N37W120.earth_relief_03s_g.nc",
+        "@S15W105.earth_synbath_30s_p.nc",
+        "@N00W030.earth_vgg_01m_p.nc",
+        "@S90E000.earth_wdmam_03m_g.nc",
+        "@N00W030.mars_relief_01m_g.nc",
+        "@N00W030.mercury_relief_01m_p.nc",
+        "@N00W030.moon_relief_01m_p.nc",
+        "@N00W030.pluto_relief_01m_p.nc",
+        "@N00W030.venus_relief_01m_g.nc",
+        # List of cache files.
         "@EGM96_to_36.txt",
         "@MaunaLoa_CO2.txt",
-        "@RidgeTest.shp",
-        "@RidgeTest.shx",
         "@RidgeTest.dbf",
         "@RidgeTest.prj",
+        "@RidgeTest.shp",
+        "@RidgeTest.shx",
         "@Table_5_11.txt",
         "@Table_5_11_mean.xyz",
+        "@capitals.gmt",
+        "@circuit.png",
+        "@earth_relief_20m_holes.grd",
         "@fractures_06.txt",
         "@hotspots.txt",
-        "@ridge.txt",
         "@mars370d.txt",
-        "@srtm_tiles.nc",  # needed for 03s and 01s relief data
+        "@ridge.txt",
+        "@srtm_tiles.nc",  # Needed for earth relief 03s and 01s data.
         "@static_earth_relief.nc",
         "@ternary.txt",
         "@test.dat.nc",