Complex sentence: Since further progress for that year was impossible, the ship was secured in winter quarters, although the members of the xpedition and the crew were aware that only a few miles of ice-blocked sea lay between them and the open waters.
Split into simpler sentences: Since further progress for that year was impossible, the ship was secured in winter quarters. Even so the members of the xpedition and the crew were aware that only a few miles of ice-blocked sea lay between them and the open waters.