Safari usually has WebGL enabled by default.

To enable WebGL manually:

Click Safari and then select Preferences.
Select the Websites tab.
Select WebGL from the list on the left side of the window. (Tip: You will only see this option if WebGL has been disabled in your browser.)
If you see oceanschool.ca listed on the right, select Allow from the drop-down menu.
If you do not see oceanschool.ca listed on the right, look for When visiting other websites in the lower-right corner of the window, and select Ask or Allow from the drop-down menu.

Troubleshooting guide