2018 & 2019 Neptune Island Waterpark Season Pass Holders are invited for an exclusive visit to the island prior to our 2019 Opening Day. Join us on Saturday, May 18, 2019 from 10 am- 7 pm for this exclusive day. All visitors to the park must present their season pass for entry. Bring-a-Friend passes may be redeemed during our Season Pass Holder day, but regular admission tickets will not be sold.