This page of the guide to Ghost of Tsushima has valuable tips on how to find secrets and collectibles easier. These include the locations marked with question marks, as well as the lesser collectibles like, e.g. records, Mongolian artifacts, and banners.
There are several ways to make finding secrets easier. The first is to equip the Traveler's Attire. One of the features of this outfit is that it makes the controller vibrate if there are any secrets in the vicinity. The vibrations increase as you approach the collectible, making it even easier to find.
You should also equip the Traveler's Attire after winning each major battle and then search the location where the fight took place. We also recommend upgrading this outfit to its maximum level - this will increase the search radius to 60 meters (the default range is 30 meters).
The second way to make finding secrets easier is to unlock skills from the Exploration category. They are:
- Wind of Health - It can help you find hot springs.
- Wind of Resolve - It can help you find bamboo strikes (mini-games involving cutting bamboo with a katana).
- Wind of Charms - It can help you find Shinto shrines.
- Wind of Inari - It can help you find fox dens (and consequently Inari shrines as well).
- Wind of Vanity - It can help you find cosmetic items, such as new headgear or masks.
Open the world map and press right on the d-pad to select the category of secrets you are interested in. Searching for big secrets (question marks) is possible after obtaining the skills mentioned above.
You can look for smaller secrets (e.g. records or artifacts) after equipping Traveler's Attire.
From now on, you can use the guiding wind to find secrets. In addition, dots will appear on the Tsushima map symbolizing the direction of travel to the next secret from a given group. It is worth noting that you don't have to ride all the way to that place. You can move to a different location by using fast travel and shorten your search time.
As for the bigger secrets, you can reveal all the question markers by capturing a given region of Tsushima - after liberating the locations controlled by the Mongols. You don't have to painstakingly discover the next parts of the map. Instead, you can go straight to the question marks to find out what they hide.