[Arubalisa]

For diving, Unique Sports http://www.visitaruba.com/uniquesports/ is right at the northern end of the Riu's property http://www.wikimapia.org/#lat=12.5679415&lon=-70.0477284&z=18&l=0&m=b and their boats leave from De Palm right in front of there as well.

For a tour see the info at http://www.aruba.com/forum/f38/bully-cerry-private-tour-39116/