A testing data set, composed of two MULTIPOLYGONs, one is the manually constructed example from sf (and silicate::sfzoo$multipolygon), the second is South Australia, with many lake-islands in the main polygon, and one artifical hole in the Kangaroo Island polygon.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.