Cattagat, a narrow sea, lying between part of Jutland and the coast of Sweden, and, towards the latter, covered with a great number of islands. It is almost closed at the extremity by the low Danish islands of Zealand and Funen, which, in ancient times, formed the seat of the Suiones. Between the former and the coast of Sweden is the Sound. These islands were anciently called Codonania, and gave to the Cattegat the name of Sinus Codonanus. Its greatest depth is thirty-five fathoms; but this decreases as it approaches the Sound, which begins with sixteen fathoms, and near Copenhagen shallows even to four. According to Pliny, the Roman fleet, under the command of Germanicus, sailed round Germany, doubled the Cimbriacum Promontorium, and arrived at the islands which fill the bottom of the Cattagat, and of which, either by observation or information, the Romans were acquainted with twenty-three. One of these they called Glessaria, from its amber, a fossil abundant to this day on part of the southern side of the Baltic. A Roman knight was employed by Nero's master of the gladiators to collect in these parts that precious production, and thereby became perfectly acquainted with this country.