The solubility of octane (1) in seawater (2) has been reported in two works:

Because temperature and salinity are not specified, the data of Freegarde et al.are rejected. The value of Krasnoshchekova and Gubergrits is considered doubtful since it is greater than the tentative value for the solubility of octane in pure water in 298 K.

References:

1 Krasnoschchekova, R. Ya.; Gubergrits, M. Ya.; Neftekhimiya 1973, 13, 885-8.
2 Freegarde, M.; Hatchard, C. G.; Parker, C. A.; Lab Pract. 1971, 20, 35-40.