海山二（Eta Carinae）是位于船底座的一个恒星系统（赤经10 h 45.1 m、赤纬−59°41m），距离太阳大约7,500至8,000光年，在北纬27°以北的地区难以看见，而在南纬30°是一颗拱极星。这个系统至少有两颗恒星，其中一颗是位于恒星生命早期阶段，质量大约是太阳150倍的高光度蓝变星（LBV），并且至少已经流失30个太阳质量。虽然它被认为还有一颗质量约为太阳30倍的沃夫-瑞叶星环绕着它较大的伴星，但海山二周围有巨大厚重的红色星云，因而很难直接的发现。它总体的光度大约是太阳的590万倍，而系统的质量估计超过150倍太阳质量 。由于它的质量和生命阶段，预期在天文学上不久的将来，它将爆炸成为一颗极超新星，目前的估计是从现在开始的10,000年至20,000年。

Eta Carinae (abbreviated to η Carinae or η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity over five million times that of the Sun, located around 7500 light-years (2300 parsecs) distant in the direction of the constellation Carina. First recorded as a 4th magnitude star, it brightened considerably over the period 1837 to 1856 in an event known as the Great Eruption. Eta Carinae became the second brightest star in the sky between 11 and 14 March 1843 before fading well below naked eye visibility. It has brightened consistently since about 1940, peaking above magnitude 4.5 in 2014. Eta Carinae is circumpolar south of latitude 30°S, so it is never visible north of latitude 30°N.