200nm to km

Do you mean nautical miles or nanometres? If it’s nautical miles, 1 NM equals 1.852 km, so 200 NM is 370.4 km—a decent coastal slog, not a Sunday stroll.

If it’s nanometres (the microscopic kind), 1 nm equals 1×10^-12 km, so 200 nm is a comically tiny 2×10^-10 km.

Pick your “nm”, and you’re either planning a voyage or measuring something smaller than a gnat’s eyebrow. Either way, maths done.