There are several fun family activities near the Dominica cruise port. Hiking through the rainforests is fun for all ages. It's safe because the island lacks native venomous snakes and spiders. Trafalgar Falls is worth seeing and is easily reached by hiking. There is a stream near the falls in which you can relax, and a fun water activity that appeals to kids is river tubing. The beaches are inviting, with several good snorkeling spots available. Visiting with the local Carib natives is also a fun activity. Visitors to their villages can view handcrafted canoes and other items used for thousands of years.
For more info, see Dominica Port Guide