Scuba Diving is possible in Unawatuna, which is a max 10 min car ride away from Galle. There seem to be many places offering this, howver the PADI diving center is next to Riddim. Certification costs around $300. They also offer a one day dive for beginners, which takes you 9 -12 meters down to see colourful corals, fish and maybe the Lord Nelson wreck (a cargo ship that ran aground 10 years ago). 

Galapita Gala,Napolian Reef  are some of the best dive sites just 10-15 minutes boat ride away from Unawatuna beach.Galapita Gala a local name for the dive site means one rock over the other,You find the first rock at 8 meter depth which lies on the second rock and the total depth will be 25 meters.You will find Eeels,Lion fish,and large groups of  many colour fish.At Napolian reef which lies again just 10 minutes boat ride from the beach a diver can see many Napolian,Groopers and lion fish and colour fishes.The depth of this dive starts at 14 meters and ends at 8 meters.

Rangoon ship wreck lies 30 meters under water about 20 minutes boat drive from the beach .This dive is a must do dive if you are an Advanced certified diver accomponied with a buddy who has experience on this site.