Anyone can do it
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First open up the Entity Beta.rar file and the water package3.rar file (download at bottom)
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Then find the sbsp.xml file in the water package3.rar and go to the plugins folder in entity beta.rar file then click halo 2 then xml now drag and drop the sbsp.xml plugin into the entity beta.rar plugin folder.
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Now open up Entity and a map with water ( I chose Zanzibar)
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Scroll down to the sbsp tag
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Go to Tools then meta editor
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Now scroll all the way down until you find Water Level for Zanzibar it's normally -3 but I changed it to 2 (10 is the highest Z cordinate for Zanzibar)
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Now just hit save at the top then sign the map and ftp and here is the outcome
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Credits
KillingForFun-making the plugin
Pokecancer- For entity beta