As of about a week ago this passed weekend, I've updated the Minecraft server to the latest release, v1.13.2. This version includes substantial changes to the aquatic environment, although most of them won't be immediately visible unless you venture off into the unexplored reaches of the server (check the map for the periphery if you're curious). However, if you harvest kelp or create bonemeal, you can grow underwater plants and kelp forests yourself.
Also since this update, I've recovered everyone's inventory from the old survival world and have placed the contents in chests near your last logout location. If you had no spawn point set, I placed the chests near the entrypoint of the world. The 3 accounts that were recovered and placed near the spawn didn't have much in the way of inventory, so it's probably not a big loss. There is a bit of a trick to getting access, so bear with me:
When you first enter the game, you'll be at the spawn "house" of the new world. This is connected via a road to other points of interest, terminating at my location. Inside the basement of the spawn house is a portal hub that takes you to each of the various worlds we've worked on: The original one we started (far left) back in 2010-2011, a creative mode world that was somewhat more recent (2015), and the old survival world that persisted the longest post 1.8-release (circa 2012-2015). All of the old inventory contents from this latter world are what I've recovered, because it's the one that peaked at the highest player count.
Inventory locations are as follows:
Grimblast's is located in his workshop in the center of his work site.
Highgrade's is located at his last project before we stopped playing, which is a square island created from terrain generation glitches, and is the location of his sky bridge.
Sunder's is located in his tree house at his newest work site.
Elade's is located on her house boat.
Trekk's is located in his mountain cabin overlooking his tree farm.
Cosh and his friend (SandmanRat I think?) both have their chests located in their inventory room they were last logged out at.
Sunder's brother has his inventory placed at the project site he was working on. His friend might not have had much inventory and may be located at the spawn.
Jargath's inventory is in the basement of his greenhouse in the desert.
There's at least two names I didn't recognize when I was restoring inventory access, including one who had apparently logged out by Grimblast's mountain top house and one that had logged in but hadn't done anything (empty inventory). I'm somewhat more suspicious of the former, because he had a minecart plus a significant amount of rail in his inventory that, given the proximity to Grimblast's location, is either pilfered goods or an odd coincidence.
To gain access to these inventories, all you have to do is take the portal immediately at the base of the stairs in the spawn house to the "Old Survival" world. From here, you will need to work your way from the spawn fortress to your respective locations. You can use the world map to help find where you were last located (obvious areas are linked above). If your name isn't in the list, be sure to check the chests at the spawn fortress first and foremost.
If you have issues with any of the above, contact me, post here, or post in Discord, and I'll get you situated.