Yeah, I've seen stingray touch pools deeper than this. Also isn't romaine lettuce not recommended for reptiles due to the low mineral and nutrient content?
I can't get over the immeasurably sad face of the loggerhead on the right...
11 rare turtles in around 25 metres squared, a space good for a single guinea pig..
Meanwhile, 5x5m is really small! Most turtles in aquaria will have a 200 m2 exhibit at least (albeit shared with other species) with a visitor walk through tunnel...