How to plot a map of Coastline with high resolution

I am working on a project that predicts ocean currents, but before I get started I need to dispaly a map of the coastline that shows the lat,lon points of each bouy I am using data from. I followed the Converting Coastline Data (GSHHG) to Shapefile Format page on Math works but I get a section of the coastline that is much too low resolution for what I am looking for. Whats the best way to get around this? the file I downloaded is "gshhg-gmt-2.3.7.tar.gz" but i can't get that to work so I am using the included gshhs_c.b.gz file on MATLAB

I get a plot like this:

but id like to get more resolution with the coastine that this map has:

workingFolder = tempdir;
files = gunzip('gshhs_c.b.gz', workingFolder);
filename = files{1};
indexfile = gshhs(filename,'createindex');
latlim =[33.25 34];
lonlim =[-119 -117.24];
S = gshhs(filename, latlim, lonlim);
delete(filename)
delete(indexfile)
S(1)
levels = [S.Level];
L1 = S(levels == 1);
L2 = S(levels == 2);
L3 = S(levels == 3);
L4 = S(levels == 4);
figure
axesm('mercator','MapLatLimit', latlim, 'MapLonLimit', lonlim)
gridm; mlabel; plabel
geoshow([L1.Lat], [L1.Lon], 'Color', 'blue')
geoshow([L2.Lat], [L2.Lon], 'Color', 'blue')
geoshow([L3.Lat], [L3.Lon], 'Color', 'blue')
geoshow([L4.Lat], [L4.Lon], 'Color', 'blue')
tightmap

Answer 1

[Tammy Viggato]

My understanding is that you need a higher resolution dataset than is currently shipped with MATLAB. There are many higher resolution datasets available which you can download and import into MATLAB. Natural Earth may be a good starting point to look for such a dataset, but to reiterate there are many good ones available depending on your specific use case.

https://www.naturalearthdata.com/downloads/

[ZBMedina]

What format needs to be downloaded and how is it imported into matlab for use?