I think it would be great if I were to, anywhere at any time, be able to look at/read all the collectibles and journals I have found throughout my adventures. Journals would be able to be read, and collectibles would either show you a simple picture of them or a full inspectable model, along with their inscriptions/descriptions.
Another option (instead of them being viewable anywhere at any time), is for there to be someplace you can go to on an island, or perhaps more specifically an outpost, to view them. You know, an NPC or something.
EDIT: @metal-ravage suggested a third option for where/how to view your collectables/journals instead of it being somewhere in the menus or at an island/NPC - "The journals should be available for viewing through the bookshelves in the ships. Each crew member will be able to view only those journals available to that individual. This way you can always consult your travelling library."