[Background]the diversity and the capacity to produce bioactive products of marine actinomycetes in the remote Arctic Ocean have seldom been studied.[Approaches]Both culture-independent and-lependent approaches were used to investigate actinomycetes in the Arctic marine sediments.Natural products were primarily investigated for representative isolates using HPLC-MS.In addition,representative genome was sequenced to explore genetic resources.[Results]Highly diverse actinobacterial communities were found inhabiting the Arctic marine sediments revealed by Miseq sequencing.A total of 298 actinomycete strains were isolated,grouped into 18 genera including Streptomyces,Nocardiopsis and Rhodococcus as the three most dominant genera.Complex natural products were potentially produced by the isolates tested.New natural products were expected according to the primary HPLC-MS analysis.The genome sequencing of a representative strain,Streptomyces sp.604F,revealed 28 gene clusters potentially encoding secondary metabolites.Some of the gene clusters were predicted to be cryptic,and possibly producing new natural products to be detected after activation of the cryptic gene clusters.In addition,a large portion of the genes predicted in the genome was new with unknown function or no similarity with known genes.[Conclusion]We found diverse actinobacterial communities inhabiting the Arctic marine sediments,and isolated actinomycetes with potential in producing various natural products.Even larger genetic capacity was shown to produce diverse secondary metabolites,indicated by genome mining.It suggests that more unknown microbial treasures than we previously expected are to be found in the Arctic Ocean.