Sitakunda Echo Park is just beside the Comilla-Chittagong Highway. It’s just 37 kilometer apart from Chittagong town, and 1 kilometer away from Shitakunda bazar. You can have taxi, or CNG auto rickshaw, or bus, or train to reach that place. For train, collect the timetable of train. You can return from Sitakunda at 7:30 using at train.
You can hire a CNG auto rickshaw, and it cost 270 taka from Chittagong to Sitakunda, and it cost 260 from Chittagong to Sitakunda. When returning from the echo park, you have to go to Shitakunda bazar first, there you’ll have plenty of CNG.