Does anybody have any ideas on how I can camouflage this thing?

Cover it with pretty planters and colorful flowers!!!

To be honest I would not cover it per say as it will draw more attention to the area. I would place tall perennial grasses in pots in the back and come in front will container plantings. Still accessible yet not as obvious.

I would make a seating/gathering area where the rounded part is. Build a circular bench around the rounded part similar to benches around trees. Buy or build a fire pit a few feet away. Set some chairs/chaise around the fire pit. For the straight sides and back, build some planter boxes slightly higher than the cover on casters so they can be rolled away for access. Your choice of plantings for the boxes. Make it part of the yard, but hidden in plain sight.

turn it into a day bed... get a cushion and pillows.. add a movable shade cover above. nice place to sit and read or nap outdoors.

I'd build a tiki hut over it with a with removable floor sections that would allow access when needed.

Almost looks like a boat. Why not turn it into one.

we have a buried septic tank in our front yard. On the off chance we need to have it pumped, it's only a 10" hose that needs to fit To the tank. I would consult with a contractor about covering most of it with concrete, then the only opening needed would be enough to create beautiful seating around table over it. To access the tank, simply move table & viola!!

I would put a piece of wood like backrest down the middle...put on lots of cushions and pillows a few small side tables ...cozy seating area

I would put an extension on the PVC pipe to bring it to the top of it cap it with PVC cap then you can back fill it with topsoil and plants, when it needs to be emptied they just have to remove the cap and feed the hose into the septic. I have done this. It works.

consider a polyurethane cover, like "fake rocks" that is light and can be removed easily and as someone else said, lots of pretty plants, or maybe even and mobile vegetable garden. Quick search: http://tgwastewater.com/

Our septic cover looks like a flip top garbage can and it is buried a couple inches deep this was suggested to us by our septic guy. Call up some septic people in your area and get some ideas and prices I plant flowers around my cap and they do just fine.

Does that full length of pipe need to be there? If you can remove the pvc pipe or most of it, do ... then ...

You could paint the top boards (plywood?) all a solid color;

Create a shallow "box" to set upside down over what appears to be an access port on the far end and use it as a pedestal on which to set a planter or bird bath or other yard décor. You could match the pedestal on the other end as well.

Paint enough squares in the center of the raised area -- the part with straight edges -- lighter or darker than the original color -- in order to create a chess/checkers board in the center of it. Use heavier plastic or melamine plates as your checkers. Create chess pieces by painting the appropriate images on similar plates.

If it gives off an objectionable odor, that would determine what choices you might have.

Cover the top with artificial grass and surround it with potted plants. Put a lounge chair on top of the grass and relax.. Build a raised bed planter on wheels to cover the whole thing and plant it with a nice assortment of veggies.

Put a sail on it and turn it in to a visual sail boat.

I would build an arbor over it copying the shape even to the rounded end then finish the wood planks and seal so they look like a nice wood deck. Hang plants , add chairs and small tables. A beautiful shady summer hangout. You could even hang lengths of cloth over the top beams and let them drape down between the beams to add a dramatic effect. Maybe even some lighting. Make it look like the elevated area was on purpose.

I have a septic tank in my front yard but nothing is showing. I agree, you have an eyesore! I have never seen one like yours. If there is an odor that's even worse! I hope you can camouflage it.❤️