One of this year's biggest surprise winners is SeaWorld Entertainment (NYSE:SEAS). Shares of the theme park operator have more than doubled in 2018, up 104% through Wednesday's close. The good news keeps coming for the once-out-of-favor entertainer, as the Justice Department has laid to rest a probe related to its IPO in 2013.

SeaWorld was initially being investigated for downplaying the investment risks in its prospectus following the debut of the brand-skewering Blackfish documentary more than five years ago. The end of the probe isn't a surprise. SeaWorld and then-CEO Jim Atchison settled up with the Securities and Exchange Commission three months ago, paying a combined $5 million without having to admit any wrongdoing. The Department of Justice probe was just the last remaining gray cloud, and now the skies seem to be as blue as SeaWorld's ocean waters.

SeaWorld Orlando's Empire of the Penguin ride.

Image source: SeaWorld Entertainment.

Learning to swim again

SeaWorld is back, though the turnaround is relative. Attendance and revenue have risen 8.7% and 9.5%, respectively, through the first nine months of 2018, but it's just clawing back at the four previous years of declines. SeaWorld's trailing revenue is still 7% below its peak 2013 levels. The stock has more than doubled this year -- and it's up 166% since bottoming out 13 months ago -- but it's essentially back to its 2013 IPO price of $27. 

The turnaround is still impressive. SeaWorld may never win over animal activists protesting keeping killer whales in captivity, but it's winning over mainstream audiences by emphasizing new rides and attractions across its portfolio over the sea life performances that made it an icon decades earlier. 

Life after Blackfish hasn't been easy for SeaWorld, and it's on its third CEO since going public five years ago. However, the ingredients are lining up just right for SeaWorld's comeback recipe. The economy is holding up, and it only helps that the country's two larger theme park operators are boosting their prices for day guests as well as annual passholders. Even SeaWorld is in the process of migrating regulars into pricier new annual passes that include enhanced perks. SeaWorld couldn't have done that as recently as a year ago, when it was still discounting aggressively to get the turnstiles clicking in the right direction.

The good times should continue into 2019. SeaWorld has new rides and attractions going into most of its parks. Only a setback in tourism or economic trends will trip up its momentum heading into 2019. SeaWorld's stock and its attendance gains are outpacing those of its peers for the first time in years, and the new market darling needs to make sure that it keeps making a big splash with investors and park guests.