There are not as many boat trips as from the Marmaris and Olu Deniz area as there are no islands off the coast of Side.There is a boat trip up the river to Manavagat where there are small waterfalls.

We went on a boat trip from Side to Alanya. We had a little time to look at Alanya then came back to Side by coach. You can find it at Side harbour and it seems to go every day.

We haven't tried the Manavgat falls one but most feedback from friends suggest it was disappointing.

You can do boat trips from Kemer which is more scenic than doing it from Alanya.It can be arranged through your tour operator in the hotel but you can always do it yourself as there is travel agents in the resorts that organise these trips which maybe cheaper.
Make sure you book an all inclusive trip as it makes such a difference.Some of the gulet cruises do not cover food/drink. We have done the trip from Kemer travelling from Side and the scenery was far better than out of Alanya.It was one the best we have done.As when we did the one out of Alanya it sailed back up the coast to our hotel !!
Enjoy your holiday we love Turkey back for our 8th holiday in July.

I might be too late replying now but there are few really good boat trips, one which takes u to another beach with river on one side that u can also swim in its amazing and u see dolpins you can go with local travel agents or thomas cook, defo worth it. The best travel agents are at the bottom of kiremithane sok past the Kingfisher pub (best pub in Side) by beach, not in center of side but not far, ask for cibi. Hope im a bit helpful.