Not sure about “safest”, or what your particular area of concern is, but agree it is probably “easiest” to stay at the port.
A 2-year old isn’t going to know, or appreciate, the difference and there is certainly enough to occupy and visually entertain a toddler. It will be easier to return to the ship for naps, food and drink when necessary, without the need for transportation. It can be very hot and the pier is a long walk.
There is certainly a pool, but not one we have ever used, as we have always gone to town or out of town beach club. Therefore I am not familiar with the depth, method of entry, or whether swim diapers are allowed.
There is no beach, but there are some man-made sandy areas.