Fun times, got stopped by gun boats from multiple nations, swamped by monsoon, had to listen to a nerous BP observer bang on about pirates.
For background:
https://en.wikipedia.org/wiki/Spratly_Islands
Interactions with gun boats were stop, talk, stand aside while people wander about, passport inspections, and (allegedly!) envelopes of cash and stacks of soft core magazines disapeared (after being left out).
If you check the Spratly Dispute link we're talking Chinese, Vietnamese, Malaysian, Borneo, etc. anybody with an interest. Often with Russian, US, UK observers | advisors from major petro companies.
Survey wise; Sea floor, subsea floor layers (for petro exploration), tidal movements.
Logging:- GPS, Differential GPS, LORAN, multichannel returns from streamer arrays (seismic) - building real time corrected 3D imaging on the fly.
Never saw a pirate, did often observe a sea of bobbing lights after dusk as "sea gypsy" ([1] et al) fisherfolk went out to catch squid in the dark.
[1] https://en.wikipedia.org/wiki/Sama-Bajau
Maps showing borders are best avoided in disputed areas - just map the physical earth forms and leave poltical boundaries off if you want to avoid trouble.
I had the same issue in the disputed areas between Pakistan and India - not the place to travel with a map showing boundaries, someone will always disagree with any line drawn.