Navigating the Sea of Constant Drift is not straightforward.
Most civilized islands will have an Celestial Navigator, an astronomer who tracks the island's location on the globe based on the stars.
Similarly, most ships will employ an Astronavigator, an expert in Navigator's Tools with the ability to cast the Sending spell. They are able to reach out to the Celestial Navigator to determine the island's location and map a direct course. Astronavigators are educated at one of prestigious Astral Navigation Academies.
Requirement: Proficiency in Navigator's Tools
Time Spent: 12 Weeks of Downtime
Cost: 300 gp per week + spell cost
Expertise in Navigator's Tools
Sending Spell
Regularly updated list of known Celestial Navigators and their island
Known Academies:
Compass Points Academy, Baeldun, South Harbour
Once completed, all nautical navigation DC's will be lowered by 10 and you will roll with advantage on any nautical navigation checks in order to reach an island if you use the sending spell to reach out to the island's Celestial Navigator.
The term 'Spellcaster' does not include innate spellcasting / species traits.
Non-Spellcasters 200 gp*
Spellcasters 150 gp
Wizards 100 gp
*using Wisdom as their spellcasting ability
Navigators not trained at Navigation Academies may also purchase a Nautical Sending Stone for 2,000 gp. These stones link into a sending stone system of Celestial Navigators.
Unfortunately, the system is corrupt as many stones have fallen into the wrong hands. As a result, there is a 10% chance of interception by privateers, pirates and other nefarious beings which aim to lead you off-course or attempt to intercept your vessel.
Successfully reaching out to the Celestial Navigator means the DC for your navigation skills will be lowered by 10.
The difficulty to navigate is dependent on the character's skills and abilities:
Ability
20 DC - Expertise in Navigator's Tools
25 DC - Proficiency in Navigator's Tool
N/A - No-Proficiency
Mitigation
Using Nautical Sending Stones or correct use of the Sending spell = DC lowered by 10
Completed the Academy = DC lowered by 10 + Advantage
Navigation based on bird observation, swell, cloud reflection and sky colours does happen in Hwaelryne. Unfortunately, it is less reliable due to the constant shifting nature of the sea and the lands, and typically requires both expertise in survival and a familiarity with the destination to succeed.
Ability DC
20 DC - Familiarity with Destination + Expertise in Survival
25 DC - Familiarity with Destination + Proficiency in Survival
35 DC - Familiarity with Destination + No-Proficiency
25 DC - Unfamiliar with Destination + Expertise in Survival
35 DC - Unfamiliar with Destination + Proficiency in Survival
N/A - Unfamiliar with Destination + No-Proficiency
Mitigation
Use of the Commune with Nature spell lowers this difficulty by 10.
A (Level 3+) Druid Circle of the Sea, or Tempest Cleric with a sea-based deity have advantage on this roll.