Two Gram-positive or Gram-variable, endospore-forming, moderately halophilic rods (strains TF-11(T) and TF-12(T)) were isolated from a tidal flat of the Yellow Sea in Korea and were subjected to a polyphasic taxonomic study. Strains TF-11(T) and TF-12(T) had cell-wall peptidoglycan based on meso-diaminopimelic acid. The predominant menaquinone found in the two strains was MK-7. The cellular fatty acid profiles of both strains contained large amounts of branched and saturated fatty acids. The major fatty acids were anteiso-C(15 : 0) and iso-C(15 : 0). The DNA G+C contents of strains TF-11(T) and TF-12(T) were respectively 49 and 38 mol%. Phylogenetic analysis based on 16S rDNA sequences showed that strains TF-11(T) and TF-12(T) fell within the radiation of the cluster comprising Bacillus species. The level of 16S rDNA sequence similarity between strains TF-11(T) and TF-12(T) was 98.3 %. Strains TF-11(T) and TF-12(T) exhibited levels of 16S rDNA sequence similarity of less than 96.0 and 96.3 %, respectively, to Bacillus species. The mean level of DNA-DNA relatedness between the two strains was approximately 7 %. On the basis of phenotypic and phylogenetic data and genomic distinctiveness, strains TF-11(T) and TF-12(T) should be placed in the genus Bacillus as two distinct novel species, for which the names Bacillus marisflavi sp. nov. (type strain TF-11(T)=KCCM 41588(T)=JCM 11544(T)) and Bacillus aquimaris sp. nov. (type strain TF-12(T)=KCCM 41589(T)=JCM 11545(T)) are proposed.