Nazjatar is an underwater zone. If they kept the water inside of it it would have been very easy to navigate it. Underwater zones are always like that. They seem broken and difficult because without the water they are. The caves, mountains of rocks, crevasses etc. makes it difficult to navigate without the water/ocean.
Also keep in mind Nazjatar had 6 zones (Naga city, ruins, coral forest, kelp forest, ashen strand and dragon’s teeth basin) squished into one tiny one. If Nazjatar was it’s own expansion (if only 
), each zone would have been easier to navigate. It would have been like how the Broken isles were. 5 leveling zones with the Naga city being the end zone like Suramar.