Midnight Mass Explained
7. Riley's Dream
A recurring image in the opening episodes is Riley sitting alone in a rowboat surrounded by miles of open water. It's a serene but ominous sight which will leave viewer's scratching their heads at this early stage as they ponder over its meaning.
Audiences won't need to wait for long, however. In an open conversation with Erin (Hill House's Kate Siegal), Riley confesses that this has been a recurring dream he's been having for some time. In it, he sits in a boat waiting to travel to a faraway shore, but he doesn't. Instead, he sits and watches the sunrise, at which point the dream ends.
Later that night he dreams he isn't by himself on the boat anymore. Erin is with him. For Riley, it's a tender realisation that he isn't alone anymore, but the dream holds much more significance.
In the next episode Riley's dream comes true. After being transformed into a vampire, he takes Erin out on a boat where he tells her what happened to him. As the sun rises, Riley bursts into flames before her eyes.
Riley wanted Erin to witness what happened so that she'd leave. However, whether Riley's dreams were divine premonitions are left purposefully ambiguous.