Advancement for riding a boat with another player

Hello, I'm trying to create an advancement for getting in a boat with another player:
{
  "parent": "arcadia:arcadia/root",
  "criteria": {
    "ride_with_another_arcadian": {
      "trigger": "minecraft:started_riding",
      "conditions": {
        "player": {
          "vehicle": {
            "passenger": {
              "type_specific": {
                "type": "minecraft:player"
              }
            }
          }
        }
      }
    }
  },
  "display": {
    "description": {
      "translate": "advancements.arcadia.adventure_for_two.description"
    },
    "icon": {
      "count": 1,
      "id": "minecraft:oak_boat"
    },
    "title": {
      "translate": "advancements.arcadia.adventure_for_two.title"
    },
    "frame": "goal",
    "hidden": true
  },
  "requirements": [
    [
      "ride_with_another_arcadian"
    ]
  ]
}

The problem is, it's triggering whenever you get into a boat. There doesn't even have to be a passenger. I'm fairly new to this so what obvious mistake am I making? 😄