An aerobic Gram-negative, slightly curved rod-shaped and non-motile bacterium, designated G5_TVMV8_7(T), was isolated from the deep sea sediment sample of the North Atlantic Ocean. Strain G5_TVMV8_7(T) displayed growth at 4-45 °C (optimum, 25-35 °C), at pH 6.0-11.0 (optimum, 7.0-8.0) and in 1.0-15.0 % (w/v) NaCl (optimum, 3.0-5.0 %). Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain G5_TVMV8_7(T) belongs to the genus Idiomarina, sharing the highest similarity with Idiomarina salinarum ISL-52(T) (97.4 %) and I. homiensis PO-M2(T) (97.1 %) followed by other validly described species of the genus Idiomarina (96.9-93.5 %). The G + C content of the genomic DNA was found to be 50.2 mol %. The digital DNA-DNA hybridization value between strain G5_TVMV8_7(T) and I. salinarum ISL-52(T) was 17.70 ± 2.24 %. The average nucleotide identity values between strain G5_TVMV8_7T and I. salinarum ISL-52(T) was found to be 70.03 %. The major fatty acids were C16:0 (12.7 %), iso-C15:0 (11.5 %) and Sum In Feature 8 (C18:1 ω7c/ω6c) (13.5 %). The predominant respiratory quinone was identified as Q-8, and the polar lipids as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol including several unidentified polar lipids. Based on the genotypic and phenotypic results, a new species Idiomarina atlantica is proposed. The type strain is G5_TVMV8_7(T) (= MCCC 1A10513(T) = KCTC 42141(T)).