Here is a previously unposted rendering:
Source: Times of Oman
http://www.timesofoman.com/article/50034/Oman/Oman-tourism:-Biggest-indoor-theme-park-to-be-ready-in-2017
This newspaper article refers only to an 'indoor water park', not a full-scale theme park:
Source: William Consulting
http://site.williamconsulting.my/main/3141/index.asp?pageid=101279&t=projects