title: Sampling sites map in R
body: <p>For my project 60 sampling sites were sampled in Betty's Bay MPA on the South African Coast. These sites are at different depths and represent different habitats.
  I am very new to programming spatial data so I really appreciate any help.</p>
  <p>I tried to follow the code from this page: <a href="https://www.r-bloggers.com/2019/10/make-a-map-of-your-study-site-with-tmap" rel="nofollow noreferrer">https://www.r-bloggers.com/2019/10/make-a-map-of-your-study-site-with-tmap</a></p>
  <p>And everything works up to the point when I want to plot the map, then the error says:
  Error: Object Coastline is neither from class sf, stars, Spatial, Raster, nor SpatRaster.</p>
  <p>Where the code says
  <code>land &lt;- st_read(dsn =&quot;LandPoly&quot;)</code>
  I coded
  <code>Coastline &lt;- st_read(dsn =&quot;RSAProvinces&quot;) Coastline &lt;- st_is_valid(Coastline, NA_on_exception = TRUE, reason = FALSE)</code> .
  RSA Provinces is a shapefile I downloaded online.</p>
  <p>What I hope for is a map of my study area with the borders of the MPA (which I have a shapefile for) and the sampling sites with a color gradient for the depths (light blue to dark blue the deeper it gets) and different shapes for the three different habitats.
  I tried with ggplot and the map &quot;world&quot; for the coastline but my area is so small that it's not detailed enough.</p>
  <p>Any suggestions?</p>