[4] In Chinese astronomy, the stars that correspond to Hydra are located within the Vermilion Bird and the Azure Dragon.

The head of Hydra was collectively known as "Min al Az'al," meaning "belonging to the uninhabited spot" in Arabic.

54 Hydrae is a binary star 99 light-years from Earth, easily divisible in small amateur telescopes.

The head of the snake corresponds to the Āshleshā Nakshatra, the lunar zodiacal constellation in Indian astronomy.

[9] U Hydrae is a semi-regular variable star with a deep red color, 528 light-years from Earth.

[1] Hydra includes GJ 357, an M-type main sequence star located only 31 light-years from the Solar System.

This star has three confirmed exoplanets in its orbit, one of which, GJ 357 d, is considered to be a "Super-Earth" within the circumstellar habitable zone.

[12] Discovered in 1785 by William Herschel, it has earned the nickname "Ghost of Jupiter" because of its striking resemblance to the giant planet.

M68 (NGC 4590) is a globular cluster visible in binoculars and resolvable in medium amateur telescopes.

Though it was discovered as a non-stellar object in 1784 by William Herschel, its status as a globular cluster was not ascertained until 1932, when Clyde Tombaugh looked at photographic plates taken of the region near Pi Hydrae on 12 May 1931.

[1] It is easily observed in skies south of 40°N latitude, found by using 1, 2, 3, and 4 Centauri as guide stars.

Large amateur telescopes - above 12 inches aperture - reveal its spiral arms, bar, and small, bright nucleus.

[1][16] In a medium-sized amateur instrument, around 8 inches in aperture, the spiral arms become visible under good conditions.

It is not perfectly symmetrical in the eyepiece, rather, the northwest side is flattened and the nucleus has a southwest-to-northeast bar.

Though most galactic disks are flat because of their rate of rotation, their conformation can be changed, as is the case with this galaxy.