Polycyclic pyridinium alkaloids are widely distributed in several sponges of the order Haplosclerida. So far, studies on Haliclona and related genera were mainly concentrated on warm or tropical waters. Here, we describe the chemical investigation of the Arctic sponge Haliclona viscosa and structure elucidation of the acyclic 1,3-dialkyl pyridinium alkaloid viscosaline. A novel structural motif of viscosaline is that beta-alanine is covalently bound to one alkyl chain.