Swimmer

#0a91bf

A blue that is muted. It is light — black text sits on it comfortably, white text does not.

Hex

#0a91bf

RGB

10, 145, 191

OKLCh

61.5% 0.121 230.0°

CIELAB (D50)

55.6, -20.3, -33.6

What is true of this colour, and of no other

11 other named colours sit within ΔE00 2 of it — this part of the space is crowded, and the names here are finer distinctions than most people make.
It sits exactly on the sRGB boundary: at this lightness and hue the gamut has nothing left, and a wider display would show a more colourful version of it.
As text on white it measures APCA Lc 63.1; on black, Lc -38.6. The sign is the polarity, which the WCAG ratio discards.
Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
protanopia and deuteranopia and tritanopia shift it by ΔE00 22.6 and 22.0 and 21.9 — no red cone.

Text on this colour

White text

3.61:1 — large text only

Black text

5.82:1 — passes AA

Black text is the better of the two at5.82:1. That is enough for body text.

As text on white, it needs to change

#0080aa is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved, and some saturation was given up to stay inside sRGB.

Try it against your own background

The same colour, with one cone missing

As you see it

#0a91bf

protanopia

#8989bf · ΔE00 22.6

deuteranopia

#7c7cc0 · ΔE00 22.0

tritanopia

#6a6aff · ΔE00 21.9

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isBlue to the Bone at ΔE00 0.603: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

Blue to the BoneΔE00 0.603 · #0190c0
Surf RiderΔE00 0.69 · #0193c2
Spa DreamΔE00 1.019 · #1993be
Hawaiian SurfΔE00 1.406 · #008dbb
Dynamic BlueΔE00 1.528 · #0192c6
Hawaiian OceanΔE00 1.528 · #008db9
Christmas BlueΔE00 1.532 · #2a8fbd
Germander SpeedwellΔE00 1.75 · #0094c8
Porpita PorpitaΔE00 1.776 · #2792c3
Hidden SpringsΔE00 1.885 · #1b8cb6
Parrotfish BlueΔE00 1.954 · #028fc4
Spinnaker BlueΔE00 2.091 · #018cb6

12 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.