where were Har Grizim and Har Eival

 וְהָיָ֗ה כִּ֤י יְבִֽיאֲךָ֙ הֹ׳ אֱלֹקיךָ אֶל־הָאָ֕רֶץ אֲשֶׁר־אַתָּ֥ה בָא־שָׁ֖מָּה לְרִשְׁתָּ֑הּ וְנָתַתָּ֤ה אֶת־הַבְּרָכָה֙ עַל־הַ֣ר גְּרִזִ֔ים וְאֶת־הַקְּלָלָ֖ה עַל־הַ֥ר עֵיבָֽל׃

הֲלֹא־הֵ֜מָּה בְּעֵ֣בֶר הַיַּרְדֵּ֗ן אַֽחֲרֵי֙ דֶּ֚רֶךְ מְב֣וֹא הַשֶּׁ֔מֶשׁ בְּאֶ֙רֶץ֙ הַֽכְּנַעֲנִ֔י הַיֹּשֵׁ֖ב בָּעֲרָבָ֑ה מ֚וּל הַגִּלְגָּ֔ל אֵ֖צֶל אֵלוֹנֵ֥י מֹרֶֽה׃

You would think that once Bn"Y crossed the Yarden they could just ask for directions, but maybe anticipating the male reluctance to do such things, the Torah has to spell out in exacting detail just where Har Grizim and Har Eival stood.

The chapter then continues and ends

 כִּ֤י אַתֶּם֙ עֹבְרִ֣ים אֶת־הַיַּרְדֵּ֔ן לָבֹא֙ לָרֶ֣שֶׁת אֶת־הָאָ֔רֶץ אֲשֶׁר הֹ׳ אֱלֹקיכֶ֖ם נֹתֵ֣ן לָכֶ֑ם וִֽירִשְׁתֶּ֥ם אֹתָ֖הּ וִֽישַׁבְתֶּם־בָּֽהּ׃

וּשְׁמַרְתֶּ֣ם לַעֲשׂ֔וֹת אֵ֥ת כׇּל־הַֽחֻקִּ֖ים וְאֶת־הַמִּשְׁפָּטִ֑ים אֲשֶׁ֧ר אָנֹכִ֛י נֹתֵ֥ן לִפְנֵיכֶ֖ם הַיּֽוֹם

Repeating again that Bn"Y will be entering the land to conquer it, but this time adding that we will be crossing the Yarden, another unnecessary detail that could have been mentioned earlier, before וְהָיָ֗ה כִּ֤י יְבִֽיאֲךָ֙ הֹ׳ אֱלֹקיךָ אֶל־הָאָ֕רֶץ אֲשֶׁר־אַתָּ֥ה בָא־שָׁ֖מָּה לְרִשְׁתָּ֑הּ

There is a strange gemara in Sanhedrin 44 that faults Yehoshua for delaying the giving of brachos on Har Grizim and Har Eival the time it takes to travel 60 mil:

 ויאמר ה' אל יהושע קום לך דריש ר' שילא א"ל הקב"ה שלך קשה משלהם אני אמרתי והיה בעברכם את הירדן תקימו ואתם ריחקתם ס' מיל 

Tos on the spot asks the obvious question: Our parsha gives directions to the mountains to give the brachos on.  Yehoshua had no choice other than to wait until they got there before fulfilling Hashem's command!

In a nutshell (I am oversimplifying), Tos answers that there is a Har Grizim and Har Eival location that is close to the Yarden, and one that is further away.  Yehoshua erred in going to the further one rather than giving the brachos and kelalos at the closer one.

Chasam Sofer suggests a different answer, one that also resolves the difficulties in the pesukim.  There is only one set of mountains called Har Grizim and Har Eival.  However, whether it is one day's journey from the Yarden or not depends.

 כִּ֤י אַתֶּם֙ עֹבְרִ֣ים אֶת־הַיַּרְדֵּ֔ן לָבֹא֙ לָרֶ֣שֶׁת אֶת־הָאָ֔רֶץ, if YOU cross the Yarden of your own accord, intent on the conquest of Eretz Yisrael, committed to Torah and mitzvos, then וּשְׁמַרְתֶּ֣ם לַעֲשׂ֔וֹת אֵ֥ת כׇּל־הַֽחֻקִּ֖יםשְׁמַרְתֶּ֣ם לַעֲשׂ֔וֹת אֵ֥ת כׇּל־הַֽחֻקִּ֖ים וְאֶת־הַמִּשְׁפָּטִ֑ים אֲשֶׁ֧ר אָנֹכִ֛י נֹתֵ֥ן לִפְנֵיכֶ֖ם הַיּֽוֹם you will fulfill the chok and mishpat of giving the brachos and kelalos immediately, that same day.  You will get to Har Grizim and Har Eival, even if they are 60 mil away, right away.  

On the other hand, וְהָיָ֗ה כִּ֤י יְבִֽיאֲךָ֙ הֹ׳ אֱלֹקיךָ אֶל־הָאָ֕רֶץ, if Hashem is the one bringing you into the land willy nilly, not because of your zechuyos, not because you are motivated, but in spite of the fact that you don't really deserve it, then הֲלֹא־הֵ֜מָּה בְּעֵ֣בֶר הַיַּרְדֵּ֗ן אַֽחֲרֵי֙ דֶּ֚רֶךְ מְב֣וֹא הַשֶּׁ֔מֶשׁ בְּאֶ֙רֶץ֙ הַֽכְּנַעֲנִ֔י הַיֹּשֵׁ֖ב בָּעֲרָבָ֑ה מ֚וּל הַגִּלְגָּ֔ל אֵ֖צֶל אֵלוֹנֵ֥י מֹרֶֽה׃, you have a long way to shlep to get to those mountains.

It is not the 60 mil delay per se that the gemara is faulting Yehoshua for, but rather it is what those 60 mil represented -- a lack readiness and motivation to fulfill the dvar Hashem, for otherwise, it would have been a minor one day journey (see Chasam Sofer d"h v'haya because I am simplifying a lot.)