On 21 January, Phillip and a party which included John Hunter, departed the Bay in three small boats to explore other bays to the north.[43] Phillip discovered that Port Jackson, about 12 kilometres to the north, was an excellent site for a colony with sheltered anchorages, fresh water and fertile soil.[43] Cook had seen and named the harbour, but had not entered.[43] Phillip's impressions of the harbour were recorded in a letter he sent to England later: "the finest harbour in the world, in which a thousand sail of the line may ride in the most perfect security ...". The party returned to Botany Bay on 23 January.[43]