Rules question
 

Please be kind with answers, I am a newbie.

So, a buddy and I are playing yesterday(stroke play).

I mishit the ball off the tea. It rolls 30 yards and goes into the water.

What are my options here?

Drop behind where it went in and hit 3?

Can I re-tee and hit 3 or would that be hitting 2?

Drop where it went in and hit 3 or re-tee and hit 3. Either way, you still have to accept the penalty stroke.

beat me to it

Option #3 - Blame your buddy for distracting you in your backswing and claim a mulligan!

I like this option!!

Thanks to everyone for their responses.

Can also drop anywhere on that 30 yd line from the tee to where it went in, I believe. If you didn't want to hit off a steep bank. Still hitting 3 no matter which.

You have three option 1. Re-tee 2. Two clubs from point of entry (already mentioned by others) 3. Keep the point of entry between you and the flag and go back as far as you want on that line. There is another option that is rarely used so I don't waste your time

Option #2 applies only if the ball is lost in a lateral hazard.

Was it a red or yellow stake hazard? That will change your options depending............

So you would consider water off tee as a lateral hazard. Isn't it implied?

Not necessarily. I've played holes where a large pond was right off (directly in front of, and going from one side of the fairway to the other) the tee boxes and you had to go around it and get to the fairway on the other side. I actually assumed this was the kind of hazard the OP was describing.

Take off your pants and go in after your ball, re-hit without penalty (ha, ha)

I guess I am used to all water being marked as either a red or yellow hazard.

Yellow stakes for a Hazard, red for a lateral hazard. Hazards are lateral if the committee determines there is no practical way to drop behind the hazard as per Rule 26/1b. (Keeping the point of entry between you and the flag.)
If you ball went in a lateral the added option is that under 1 stoke penalty at the point where you ball crossed the margin you can drop withing two club lengths, no nearer the hole. Or you can drop on the other side of the lateral on the same line as your ball entered you can take two cub lengths no nearer the hole.

Back to the original question yes, play from where the last stroke was played under penalty of stroke and distance (the first one counts). Or keep the point where your ball entered between you and the flag and drop anywhere along that line you wish.

Since you've gotten some good answers, rather than start one myself I'm going to hijack your thread and ask some more rules questions:

Our fringe today was thick, and a guy was on the fringe, but overhanging the green noticeably (if it were overhanging the green like this you'd wait the full 10 seconds before tapping it in). The rule says to be on the green (and hence able to mark clean and place) you have to touch the green. If the fringe were shorter the ball would have been touching. He asked and I told him likely it doesn't count as technically on the green. Agree?

It's not on the green if it's not touching the green.

Smalls would be right here. It's either touching the green or it isn't. There's no in between as far as I know.

Here is the definition of putting green from usga.org:

Putting Green
The “putting green’’ is all ground of the hole being played that is specially
prepared for putting or otherwise defined as such by the Committee. A ball is
on the putting green when any part of it touches the putting green.

Two clarifications, one response was that the golfer had the option to drop anywhere along the flight of the ball to the hazard which is a common misconception. As many have pointed out, you may drop as far back as you want as long as the point where your ball entered the hazard is between you and the flag.

Another response referred to the opposite side of a lateral hazard "on the same line as your ball entered" which I wasn't sure what was meant. You may drop on the opposite side of a lateral hazard equidistant from the flag as the point your ball entered the hazard. For example, if your ball entered a lateral hazard 50 yards from the flag, you may drop within two club lengths of a spot 50 yards from the flag on the opposite side of the lateral hazard. No nearer, no further, it must be equidistant.

Calling Fourputt.