It's a feature of aquatic plants, they do have the evolutionary habit of meshing together with the intention of staying put where they like.

Perhaps that's how many species came to survive floods, storms and torrents in the wild...

Sumo wrestlers, excavating equipment, machetes can have a hard time cutting hacking or pulling on that titanic mass, for sure

One thing you have going for you, it's a lined pond, making it a monster mass kinda sorta under control

Draining the pond completely and allowing it to get close to drying out will make like easier, when the bulk of the water is gone, the titanic carpet may lift in sections a lot easier, like a rug, unless, you let loose a huge amount of stone, dirt and pebbles

When close to dry, rip the pots out first, then you can roll the meshed loose plants out easy. With the bulk of the water gone, the mass will be a lot lighter to lift

Take care when taking a grip on the mass, if there are dragonfly larvae a bit uppity among it, they can and will deliver a severe bite

Regards, andy
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