not sure what seaside beach is, but if it's in front of oceana, or by the las palmas, then there is a bathroom right there. i think it has one stall, mayyyyybe two, and is still available to the public. if seaside beach is in front of seaside grill, then i have no clue where the bathroom is, but i would assume that since it's near a bunch of restaurants, there would be a lot more traffic.