Far Ultraviolet Spectroscopic Explorer observations of the blue compact dwarf galaxy Markarian 59

New Far Ultraviolet Spectroscopic Explorer (FUSE) far-UV spectroscopy of the nearby metal-deficient (Z(circle dot)/8) cometary blue compact dwarf (BCD) galaxy Markarian (Mrk) 59 is discussed. The data are used to investigate element abundances in its interstellar medium. The H I absorption lines are characterized by narrow cores that are interstellar in origin and by broad wings that are stellar in origin. The mean interstellar H I column density is similar to 7x10(20) cm(-2) in Mrk 59. No H-2 lines are seen and N(H-2) is greater than or similar to 10(15) cm(-2) at the 10 sigma level. The lack of diffuse H-2 is due to the combined effect of a strong UV radiation field that destroys the H-2 molecules and a low metallicity that leads to a scarcity of dust grains necessary for H-2 formation. P Cygni profiles of the S VI lambdalambda933.4, 944.5 and O VI lambdalambda1031.9, 1037.6 lines are seen, indicating the presence of very hot O stars and a stellar wind terminal velocity of similar to1000 km s(-1). By fitting the line profiles with multiple components having each a velocity dispersion b=7 km s(-1) and spanning a radial velocity range of 100 km s(-1), some of which can be saturated, we derive heavy element abundances in the neutral gas. We find log N(O I)/N(H I) = -5.0+/-0.3 or [O I/H I] = -1.5 for the neutral gas, about a factor of 10 below the oxygen abundance of the supergiant H II region, implying self-enrichment of the latter.