(Rava): The following is obvious to me - water on top of water is considered Nach (if one takes some of the water resting in a Kli or another place, this is considered Akirah);

If a nut is floating on water, it is not Nach;

Question (Rava): If a nut is in a vessel floating on water, what is the law?

Do we focus on the nut in the vessel, and consider it Munach?

Or, do we focus on the vessel in the water, and say that it is not Munach, for it moves?

This question is not resolved.

R. Yochanan ben Nuri and Chachamim argue about oil floating on top of wine:

(Mishnah): If [Terumah] oil is floating on top of [Terumah]wine and a Tevul Yom touched the oil, only it is Nifsal (they are not considered connected, we do not consider it as if he touched the wine; the oil is only a Shelishi l'Tumah, it cannot Posel the wine);

R. Yochanan ben Nuri says, they are connected (both are Nifsalim).

(Abaye): If a pit 10 deep and eight Tefachim wide is in Reshus ha'Rabim, and one threw a mattress inside, he is liable;

If the mattress divided it into two halves, he is exempt [because each half is less than four wide. (Me'iri - in this case he intended to leave the mattress there to divide it; in the previous case, even though 10 Tefachim do not remain above the mattress, he had no intent for Bitul. Others explain that really, the pit was deeper than 10, 10 Tefachim remain above the mattress.)

Abaye holds that a mattress is Mevatel a Reshus [even though people usually do not leave it there] - all the more so a Chulyah is Mevatel;

R. Yochanan asked whether or not a Chulyah is Mevatel - surely, he holds that a mattress is not Mevatel!

(Abaye): If a pit was 10 deep and four wide and one threw something inside:

If the pit was full of water, he is liable; if it was full of produce, he is exempt.

Question: What is the reason?

Answer: Water is not Mevatel a Reshus (Rav Hai Gaon - the Mechitzos are still noticeable), produce is Mevatel.

Support (Beraisa): If one threw from the sea into an intercity road (from Karmelis to Reshus ha'Rabim) or vice-versa, he is exempt;

R. Shimon says, if there is a ditch 10 deep and four wide [in the sea floor] in the place to or from which he threw, he is liable (water is not Mevatel Reshus ha'Yachid).

(Mishnah): If one threw something four Amos at a wall - if this was above 10, it is as if he threw in the air (he is exempt);

If this was below 10, it is as if he threw on the ground;

If one threw four Amos on the ground he is liable.

(Gemara) Question: When it was below 10, why is he liable - there was no Hanachah [outside of four Amos, for it bounces back]!

Answer (R. Yochanan): The case is, he threw a fat fig-cake [it stuck to the wall].

(Rav Yehudah): If one threw above 10 and it landed in a small hole [less than four by four], R. Meir and Chachamim argue about whether or not he is liable:

R. Meir says [regarding Mezuzah, and would also say here] Chokekim Lehashlim (if there is a small hole in something thick, we consider it as if the entire thickness was carved out - therefore, if the wall is four by four, it is as if the hole is four by four);

Chachamim do not say Chokekim Lehashlim.

Support (Beraisa - R. Meir): If one threw above 10 and it landed in a small hole, he is liable;

Chachamim exempt.

(Rav Yehudah): If the sides of a mound rise 10 Tefachim over the course of four [horizontal] Amos (they are too steep to walk up, they are considered Mechitzos), and one threw something [in Reshus ha'Rabim] and it landed on top, he is liable.

Support (Beraisa): If a Mavuy is level but the opening to Reshus ha'Rabim is sloped, or if it is sloped but the opening to Reshus ha'Rabim is level, it does not require a Lechi (vertical post) and Korah (horizontal beam) to permit carrying inside it;

R. Chanina ben Gamliel says, if the sides of a mound rise 10 Tefachim over the course of four Amos, and one threw something and it landed on top, he is liable.

(Mishnah): If one threw within four Amos and it Nisgalgel (rolled; Rashi - was blown) outside of four Amos he is exempt;

If he threw outside of four Amos and it Nisgalgel inside of four Amos, he is liable.

(Gemara) Question: [In the Seifa,] why is he liable - there was no Hanachah [outside four Amos]!

Answer (R. Yochanan): The case is, it rested on something [outside four Amos, then rolled back].

Support (Beraisa): If one threw outside of four Amos and the wind blew it back inside four Amos, even if it later took it outside four Amos, he is exempt;

If the wind held it stationary for a moment, even if it later blew it back inside four Amos, he is liable.

(Rava): According to Chachamim (who do not say Kelutah k'Mi she'Hunchah, they exempt one who threw from Reshus ha'Yachid to Reshus ha'Yachid through Reshus ha'Rabim), if one threw within three Tefachim on the ground he is exempt unless it landed on top of something.

Question (Ravina): We already know this from our Mishnah! R. Yochanan established that it rested on something [outside four Amos, then rolled back - he did not simply say that it was within three]!

Answer (Mereimar): Our Mishnah is when it Nisgalgel - then, it will not stop (therefore he is exempt unless it rested on something);

Rava teaches about when it is not Misgalgel - since it will stop, he is liable even if it did not rest on something!

(Mishnah): If one throws four Amos at sea, he is exempt;

If many people walk through [gravel covered by] a puddle, one who throws four Amos in it is Chayav.

The puddle discussed is less than 10 Tefachim (Ritva - if it is deeper than 10 it is a Reshus ha'Yachid; Rashi - it is Karmelis; Mishnah Berurah (345 48) - perhaps Rashi agrees that mid'Oraisa it is Reshus ha'Yachid);

If one throws into a puddle that many people walk through, he is liable.

(Gemara) Question: We understand why the Mishnah mentions 'walking' twice - this teaches that walking with difficulty is considered walking, but usage with difficulty is not considered usage;

But why does it mention 'puddle' twice?

Answer #1 (Rava): This is to teach that this applies in summer and winter:

Had it only taught about summer, we would have thought that that is because people often go there to cool off (but in winter it is not Reshus ha'Rabim);

Had it only taught about winter, we would have thought that that is because people's garments are dirty anyway, so people often go there (but in summer it is not Reshus ha'Rabim).

Answer #2 (Abaye): This is to teach that this is even if it is four Amos:

One might have thought that it is Reshus ha'Rabim only if it is less than four Amos, but if it is four Amos, people go around it and do not go through it - the repetition teaches that this is not so.

Answer #3 (Rav Ashi): This is to teach that this is even if it is less than four (Rashi - Amos; Rambam - Tefachim):

One might have thought that it is Reshus ha'Rabim only if it is four, but if it is less, people step over it and do not go through it - the repetition teaches that this is not so. (Rashash questions Rashi, for even three Amos is too big to step over. Rashi himself (113B) says that the size of a normal step is one Amah. This is not difficult for the Rambam - since a person's foot is about half an Amah, if the puddle is four Tefachim, if one takes normal steps, part of his foot will be in the puddle.)

This is like Rav Ashi taught elsewhere:

(Rav Ashi): If one threw something and it landed on a plank of a bridge that is not in line with the others, [even though some people skip over it, since others walk on it] he is liable.

(Mishnah): If one throws from the sea to the land or vice-versa, or from the sea to a ship or vice-versa, or from one ship to another, he is exempt;

If ships are tied to each other, one may carry from one to the other; if they are not tied, even if they are near each other, one may not carry from one to the other.

(Gemara - Rav Huna): If one extends a ledge of any size out of a Sefinah (ship), he may draw water from the sea (this will be explained);

(Rav Chisda and Rabah bar Rav Huna): He must extend an area four by four [Tefachim, surrounded by short walls] to permit drawing water.

(All agree that Karmelis extends up to 10 Tefachim, above this is Makom Patur.) Rav Huna says that a ledge of any size suffices - he holds that Karmelis begins at the sea floor, the air above the water is Makom Patur;

Letter of the law, he does not need any ledge to draw water - it is required for a mere Heker (so people will not take from a proper Karmelis).

Rav Chisda and Rabah require an area four by four - they hold that Karmelis begins at the surface of the water, all the water is like a thick floor;

If he will not make an area four by four, he takes from Karmelis to Reshus ha'Yachid!

Question (Rav Nachman): Rav Huna says that a ledge of any size suffices - sometimes the water is shallow, i.e. less than 10 Tefachim above the sea floor, and he takes from Karmelis to Reshus ha'Yachid!

Answer (Rabah bar Avuha): We have a tradition - 'Sefinah' refers to a big ship that does not go in water less than 10 Tefachim.

Question: The prow (front) of the ship is above the water, there the water can be less than 10 (perhaps one will draw from there)!

Answer (Rav Safra): People at the prow hold poles in the water and feel for the ground to ensure that the ship will not go into water less than 10 [lest it get stuck].

Question (Rav Nachman bar Yitzchak): Rav Chisda and Rabah require an area four by four - according to them, how may one dump wastewater out of a ship?

Suggestion: Perhaps they spill it out of the four by four area for drawing water!

Rejection: If so, he would despise that place (he would not draw water from there any more)!

Answer: He pours the water on the side of the ship, it descends to the sea by itself.

Question: Even though he does not pour it directly into the sea, his Ko'ach (impetus) causes it to go to the sea!

Answer: Chachamim did not forbid Ko'ach regarding Karmelis.