If under the effects of a Fly spell, can you move at a speed of 60 feet underwater?



A character's speed is:

Every character and monster has a speed, which is the distance in feet that the character or monster can walk in 1 round.

Using the swimming rules you can use this speed to swim, but it costs 1 foot extra per foot:

Each foot of movement costs 1 extra foot (2 extra feet in difficult terrain) when you’re climbing, swimming, or crawling.

A creature can have various special speeds such as "swim speed", "climb speed", "burrow speed", etc. However, these only apply to that one particular type of movement. Not for climbing and swimming:

You ignore this extra cost if you have a climbing speed and use it to climb or a swimming speed and use it to swim.

Nor for burrowing nor flying:

A monster that has a burrowing speed can use that speed to move through sand, earth, mud, or ice. A monster can't burrow through solid rock unless it has a special trait that allows it to do so.


A monster that has a flying speed can use all or part of its movement to fly

Climb speed is for climbing. Swim speed is for swimming. Burrowing speed is for burrowing. Flying speed is for flying.

There is no indication that these speeds are interchangeable. You cannot use your swimming speed to climb, you cannot use your burrow speed to fly, you cannot use your flying speed to swim.

  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$
    – Rubiksmoose
    Dec 10 '19 at 7:06

Swimming is not flying

As far as I am aware, flying is never defined as a game term, which means the word takes its normal English meaning: moving through the air under one's own power. I don't think most people would describe underwater movement as flying (except metaphorically).

You can probably "fly" at half speed underwater

The rules for swimming state that:

Each foot of movement costs 1 extra foot (2 extra feet in difficult terrain) when you’re climbing, swimming, or crawling. You ignore this extra cost if you have a climbing speed and use it to climb, or a swimming speed and use it to swim.

It doesn't say you need to use your walking speed, it just says that you need to use twice as much movement as normal. Hence, you could probably use the 60 feet of flight-based movement from the Fly spell to travel 30 feet per round underwater, which is still an improvement over the 15 feet per round that you'd get with the typical walking speed of 30. (But you should ask your DM how this will work in their game if you're making a plan that relies on it.)

  • \$\begingroup\$ Even if this answer does not answer the question of "flying underwater" per say, I still think it is the best answer that can be provided considering RAW. RAI I would personally allow a flying character diving into water to have a bonus from his momentum on the round in which he enters the water ... but unless he starts swimming (or climbing, lol) underwater, I'd rule that he can move at half his speed as the rules states. Flying is not swimming and a GM has to keep the flavor of water based characters alive in allowing them to be better underwater. \$\endgroup\$
    – Catar4
    Aug 9 '19 at 3:28
  • \$\begingroup\$ So if something were to prevent your ability to swim (using magical means, not physical restriction), would you still be able to "fly" underwater at a speed of 30 feet? \$\endgroup\$ Aug 9 '19 at 11:50
  • 2
    \$\begingroup\$ @Parrotmaster: True, but those aren't magical restrictions, those are just physical impediments of one form or another. If you're flying with wings, the same restrictions would apply; if you're flying because the rules of physics gave up (magic), they wouldn't. \$\endgroup\$ Aug 9 '19 at 14:45
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    \$\begingroup\$ I'd be careful suggesting the last paragraph (although I like it). I can already sense my players asking "so if I have extra climbing speed, I can use it to swim with 2 to 1 ratio too?" \$\endgroup\$
    – Vylix
    Aug 12 '19 at 7:18
  • 1
    \$\begingroup\$ @Vylix If you want a reasonable justification against it, you could say that the rule about swimming & climbing consuming 2 feet of movement for every 1 foot must be referring your walking speed and nothing else, because in the context of the rules at that point, walking speed is the only kind of speed that has been introduced. (Admittedly this is a sketchy argument, relying on the order the rules are presented.) \$\endgroup\$ Aug 14 '19 at 9:11

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